You've used Claude in the browser. Now you're going to use it where professionals do — in your terminal, with your files, building real things. This module gets you from zero to your first working session.
⏱ ~20 min
🏗 Project: your first CLAUDE.md
⚡ Day 1 ready
💡 What is Claude Code — and why does it matter?
Claude in the browser is a conversation. Claude Code is a collaborator that lives inside your project. The difference is fundamental:
CLAUDE.AI (BROWSER)
You describe what you want
It gives you text / code snippets
You copy-paste manually
Context resets each conversation
Can't see your actual files
CLAUDE CODE (TERMINAL)
It reads and writes your files
Runs commands on your machine
Remembers your project context
Understands your codebase
Takes actions, not just suggestions
The mental shift: Stop thinking of Claude as something you ask questions to. Start thinking of it as a capable colleague who can do the work — not just describe it.
What you can build from Day 1
Web apps and landing pages — fully styled, light/dark mode, deploy-ready
Automated workflows — scheduled tasks, file processors, data pipelines
Documents and decks — PDFs, PPTX, reports generated from your data
APIs and backend logic — REST endpoints, integrations, database queries
Multi-agent systems — background agents working while you do other things
⚙️ Installation
Claude Code is a CLI tool that runs on macOS, Windows, and Linux. Before installing it, you need two things: Node.js 18+ and an Anthropic account. Pick your OS below and follow each step in order.
Step 1 — Install Node.js (if you don't have it)
Open Terminal (press Cmd + Space, type Terminal, hit Enter) and run:
bash — Terminal
# Check if Node is already installed (need v18+)
node --version
# If not installed or below v18, install via Homebrew:# 1. Install Homebrew first (if you don't have it)
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
# 2. Then install Node
brew install node
# Confirm it worked
node --version # should show v18.x or higher
npm --version
Alternative: Download the macOS installer directly from nodejs.org → click the LTS version → run the .pkg file.
Step 2 — Install Claude Code
bash — Terminal
npm install -g @anthropic-ai/claude-code
# Verify the install
claude --version
Permission error? If you see EACCES: permission denied, run: sudo npm install -g @anthropic-ai/claude-code and enter your Mac password.
Step 3 — Authenticate
bash — Terminal
# This opens a browser window to log in with your Anthropic account
claude login
Your browser will open the Anthropic login page. Sign in (or create a free account). Once done, return to Terminal — you'll see ✓ Authenticated.
Step 4 — Launch in a project folder
bash — Terminal
# Navigate to any folder (or create a new one)
mkdir ~/my-first-claude-project
cd ~/my-first-claude-project
# Launch Claude Code
claude
# You'll see:✓ Claude Code — ready
❯
Step 1 — Install Node.js
Go to nodejs.org, download the LTS Windows Installer (.msi), and run it. Accept all defaults. This also installs npm automatically.
After installing, open Command Prompt or PowerShell (press Win + R, type cmd, press Enter) and confirm:
cmd / PowerShell
node --version # should show v18.x or higher
npm --version
Not recognized? Close and reopen Command Prompt after the Node install — Windows needs a fresh shell to pick up the new PATH entries.
Step 2 — Install Claude Code
In the same Command Prompt or PowerShell window:
cmd / PowerShell
npm install -g @anthropic-ai/claude-code
REM Verify the install
claude --version
PowerShell execution policy error? Run this first: Set-ExecutionPolicy -Scope CurrentUser RemoteSigned, then retry the npm install.
Step 3 — Authenticate
cmd / PowerShell
REM Opens a browser login window
claude login
Your browser opens the Anthropic login page. Sign in, then return to Command Prompt — you'll see ✓ Authenticated.
Step 4 — Launch in a project folder
cmd / PowerShell
REM Create a new folder and open Claude Code inside it
mkdir %USERPROFILE%\my-first-claude-project
cd %USERPROFILE%\my-first-claude-project
claude
REM You'll see:✓ Claude Code — ready
❯
Recommended: Use Windows Terminal (free from the Microsoft Store) instead of the old Command Prompt — it supports colors and is much easier to use with Claude Code.
Step 1 — Install Node.js
Open your terminal and install Node.js using your distro's package manager:
npm install -g @anthropic-ai/claude-code
# Verify
claude --version
Permission error? Avoid using sudo npm install -g. Instead, fix npm's global directory ownership: mkdir ~/.npm-global && npm config set prefix '~/.npm-global', then add export PATH=~/.npm-global/bin:$PATH to your ~/.bashrc or ~/.zshrc and reload: source ~/.bashrc.
Step 3 — Authenticate
bash
# Opens browser login (or use API key — see below)
claude login
Headless / no browser? Set your API key directly: export ANTHROPIC_API_KEY=your-key-here. Add it to ~/.bashrc or ~/.zshrc to make it permanent.
Step 4 — Launch in a project folder
bash
# Create a folder and launch Claude Code inside it
mkdir ~/my-first-claude-project && cd ~/my-first-claude-project
claude
# You'll see:✓ Claude Code — ready
❯
All platforms: Always launch claude from inside your project directory. Claude uses that path as its root — it reads and writes files relative to wherever you launched it.
🚀 Your First Session — Anatomy of a Good Prompt
The biggest mistake beginners make is under-briefing Claude. It has full context of your project — use that. A great prompt has three parts:
WHATWhat you want Claude to build or do — be specific
CONSTRAINTSFormat, style, tech stack, things to avoid
OUTCOMEWhat "done" looks like — file created, feature working, etc.
Weak vs. Strong prompts
✗ WEAK
"Make a landing page"
✓ STRONG
"Create index.html — a landing page for a SaaS productivity tool. Use a dark default with light mode support. Hero section, 3 feature cards, and a CTA button. No frameworks, just HTML/CSS."
Key slash commands to know right now
/helpShow all available commands
/clearClear conversation context (start fresh)
/compactCompress context to save tokens
/modelSwitch between Opus, Sonnet, Haiku
/statusSee current model, costs, session stats
EscapeCancel current generation mid-stream
🧠 CLAUDE.md — Your AI's Permanent Memory
CLAUDE.md is a plain text file in your project root. Claude reads it automatically at the start of every session. It's how you give Claude persistent context so you never re-explain your project, preferences, or rules.
Think of it as onboarding a colleague. Anything you'd tell a new developer joining the project belongs in CLAUDE.md — tech stack, conventions, what to avoid, who the user is.
What to put in it
markdown — CLAUDE.md
# Project: My SaaS App## Stack- Frontend: plain HTML/CSS/JS (no frameworks)- Backend: Node.js + Express- DB: PostgreSQL## Conventions- All files use kebab-case naming- CSS uses CSS custom properties, no preprocessors- No jQuery — vanilla JS only## What to avoid- Don't install new npm packages without asking- Don't rewrite files from scratch unless asked## Me- I'm Rick — technical background, building solo- Prefer concise responses, no filler text
CLAUDE.md best practices
Be specific about stack — saves Claude from guessing and prevents wrong assumptions
State what NOT to do — "don't install new packages" is more valuable than "use npm carefully"
Add your preferences — concise vs. verbose, comments in code vs. none, etc.
Update it as you learn — every time you correct Claude, consider if that correction should live here permanently
Keep it tight — 50–150 lines max. Claude reads all of it, every session
Global vs. Project memory: You can also place a CLAUDE.md in ~/.claude/ for preferences that apply to every project (your name, your general style, never-do rules).
⌨️
Live Terminal Sandbox
Interactive
Type a command or click a quick command below
❯claude
✓ Claude Code v1.x — connected
Model: claude-sonnet-4-6 · Project: my-app
Try a command below, or type your own. Press Enter to run.
❯
🎯 Challenge — Do it for real
Open your actual terminal alongside this page. Complete all three steps in your own Claude Code session.
1Launch Claude Code in any project folder on your machine. Type claude and confirm it starts. If you don't have a project, run mkdir test-project && cd test-project && claude.
2Run /status and note which model you're on. Then run /help and skim the output — find one command you didn't know existed.
3Ask Claude to create a CLAUDE.md for your project. Use this prompt: "Create a CLAUDE.md for this project. Ask me 3 questions first to understand the stack and my preferences."
🏗 Mini Project — Your First CLAUDE.md
Pick your operating system first — the steps will show you exactly what to type for your machine. Check each step off before moving to the next.
Step 1 — Open your terminalThe terminal is where Claude Code lives. Here's how to open it.
Press Cmd + Space to open Spotlight, type Terminal, then press Enter. The Terminal app opens — you'll see a window with a blinking cursor.
Prefer a better terminal? Download iTerm2 (free) for a much nicer experience with colors and split panes. But the built-in Terminal works fine to start.
Press Win + R, type cmd, press Enter. A black Command Prompt window opens.
Or for a better experience: open the Start menu, search for Windows Terminal, and install it from the Microsoft Store (free). It supports colors and is much easier to use.
PowerShell vs Command Prompt: Either works. If you see a blue window, that's PowerShell — also fine. All commands in this tutorial work in both.
Press Ctrl + Alt + T — this opens the default terminal on most Linux distros (Ubuntu, Mint, Pop!_OS). If that doesn't work, right-click your desktop and look for Open Terminal, or search your app launcher.
Using a remote server or SSH? You're already in a terminal — skip ahead to Step 2.
Once open, you'll see a prompt showing your current location — something like ~ (Mac/Linux) or C:\Users\YourName (Windows). That's your home directory. Think of the terminal as a text-based file explorer: you type commands to move around and create things.
Step 2 — Create a project folder and open itClaude needs a folder to work in — everything it reads and writes stays inside it.
Type these two commands, pressing Enter after each one:
macOS — Terminal# Creates the folder inside your home directory
mkdir ~/my-first-project
# Moves you inside it (cd = change directory)
cd ~/my-first-project
Your prompt will now show my-first-project — that means you're inside it. To double-check, type pwd and press Enter — it will print the full path.
Using an existing project? Skip mkdir and just run cd ~/path/to/your/project. For example: cd ~/Documents/my-website.
Type these two commands, pressing Enter after each one:
Windows — Command Prompt or PowerShellREM Creates the folder inside your user folder
mkdir %USERPROFILE%\my-first-project
REM Moves you inside it
cd %USERPROFILE%\my-first-project
Your prompt will now end with my-first-project> — that means you're inside it. To confirm your location, type cd with no arguments and press Enter — it prints the full path.
Using an existing project? Skip mkdir and run cd C:\Users\YourName\path\to\project instead.
Type these two commands, pressing Enter after each one:
Linux — bash / zsh# Creates the folder in your home directory
mkdir ~/my-first-project
# Moves you inside it
cd ~/my-first-project
Your prompt will show my-first-project. Type pwd to print the full path and confirm you're in the right place.
Using an existing project? Just run cd ~/path/to/your/project and skip the mkdir step.
Step 3 — Verify the install and launch Claude CodeOne check, then one command to start your first session.
First, confirm Claude Code is installed:
all platforms
claude --version
You should see a version number like 1.x.x.
"command not found"? npm didn't add Claude to your PATH. Run: export PATH="$HOME/.npm-global/bin:$PATH" then try again. To make it permanent, add that line to ~/.zshrc and run source ~/.zshrc.
"not recognized"? Close the terminal window completely and reopen it — Windows needs a fresh session to see newly installed commands. If it still fails, re-run the npm install step from the Installation section above.
"command not found"? Your npm global bin isn't on the PATH. Run: export PATH="$HOME/.npm-global/bin:$PATH", then add that line to ~/.bashrc or ~/.zshrc and run source ~/.bashrc.
Now launch Claude Code from inside your project folder:
all platforms
claude
# Expected output: ✓ Claude Code — ready ❯
That ❯ prompt is Claude waiting for your first message. You are now inside a session.
Asked to log in? Type claude login — your browser opens the Anthropic login page. Sign in, return to the terminal, and run claude again.
Step 4 — Ask Claude to create your CLAUDE.mdSame on all platforms — Claude prompts work identically everywhere.
At the ❯ prompt, type this and press Enter:
claude prompt — type at the ❯ cursor
I'm starting a new web project. Ask me 3 short questions to understand my stack and preferences, then create a CLAUDE.md file for this project.
Claude will ask things like "What tech stack are you using?" Answer in plain English. After your answers it writes CLAUDE.md directly to your project folder — a real file on your disk.
To see what it wrote:
claude prompt
Show me what's in the CLAUDE.md you just created.
Want to see the file outside Claude? Open Finder, press Cmd + Shift + H to go to your home folder, then open my-first-project — you'll see CLAUDE.md there.
Want to see the file outside Claude? Open File Explorer, navigate to C:\Users\YourName\my-first-project — CLAUDE.md will be there. Double-click to open it in Notepad.
Want to see the file outside Claude? In your terminal, type cat ~/my-first-project/CLAUDE.md to print its contents, or open it in your text editor of choice.
Step 5 — Ask Claude to build one real thingClaude now has your CLAUDE.md context. Watch it use it automatically.
At the ❯ prompt, ask for something concrete:
claude prompt — change to suit your project
Create a simple index.html homepage for this project. Use the stack and conventions from CLAUDE.md.
Claude will read your CLAUDE.md, then write the file. When done it shows a summary of what was created. Check your project folder — the file is really there.
Not sure what to ask for? Try: "Create a README.md that describes this project" or "Create a styles.css file following the conventions in CLAUDE.md."
Step 6 — Compress context and keep goingLearn to manage long sessions without starting over.
/compact summarizes your session history into a tight snapshot so you keep working without burning through your context window. Type it at the ❯ prompt:
claude command — all platforms
/compact
Claude confirms the compression. Now send a new request — it still knows your project:
claude prompt
Add a navigation bar to index.html — keep it consistent with the existing style.
To exit Claude Code: type /exit or press Ctrl + C. Your files stay on disk exactly as Claude left them.
To exit Claude Code: type /exit or press Ctrl + C. On Windows you may see a confirmation prompt — press Y then Enter.
To exit Claude Code: type /exit or press Ctrl + C. Your files stay on disk exactly as Claude left them.