Claude Code for Beginners

What is Claude Code?

Claude Code is Anthropic's official AI coding assistant that runs in your terminal. Unlike AI tools embedded in an editor (Cursor, GitHub Copilot, Windsurf), Claude Code is an autonomous agent — it can read your files, run commands, write multi-file edits, run tests, and reason about your entire project in one conversation.

The key insight for beginners: you don't paste code into a chat window. Claude Code reads your actual files directly. You just describe what you want, and Claude does the work.

What Claude Code can do out of the box

• Read any file in your project by path
• Write, edit, and create files
• Run shell commands (tests, builds, linters)
• Search your codebase for patterns and symbols
• Create git commits and pull requests
• Use external tools via MCP (databases, APIs, browsers)
• Orchestrate parallel sub-agents for complex tasks

Installation

# Check your Node version
node --version   # must be v18.0.0 or higher

# If not installed: https://nodejs.org (LTS version)

npm install -g @anthropic-ai/claude-code

# Run claude in any directory to trigger login
claude

claude --version
# claude-code/1.x.x linux-x64 node-v22.x.x

Your First Session

Navigate to a real project directory (not an empty folder). Claude Code is most useful when it can read actual code.

cd ~/my-project
claude

> What does this project do? Give me a brief summary of the main files.

> /plan Add a function to utils.js that formats a phone number as (XXX) XXX-XXXX

git diff

> Write a conventional commit message for these changes

# Then in your terminal:
git add utils.js
git commit -m "feat(utils): add formatPhoneNumber helper"

# Exit Claude Code
> /exit   (or Ctrl+C)

Essential Commands for Beginners

Claude Code has slash commands that control its behaviour. These are the ones you'll use every day:

Keyboard shortcuts

• Enter — submit your message
• Shift+Enter — new line without submitting (for multi-line prompts)
• ↑ / ↓ — navigate message history
• Ctrl+C — exit Claude Code
• Esc — interrupt a running action

Setting Up CLAUDE.md — Your Project Brief

CLAUDE.md is the single most impactful thing you can add to a project. It's a plain markdown file in your project root that Claude reads at the start of every session. It's your persistent "briefing document."

Without CLAUDE.md, you re-explain your project every session. With a good CLAUDE.md, Claude knows your stack, conventions, and constraints from the first message.

Minimal CLAUDE.md template

# My Project

## What this is
A Node.js REST API for managing user accounts. Connects to a PostgreSQL database.

## Tech stack
- Node.js 22, Express 5, PostgreSQL 16
- Tests: Jest + Supertest (run: npm test)
- Linter: ESLint (run: npm run lint)

## Conventions
- Use async/await, never callbacks
- All functions must have JSDoc comments
- API errors return { error: "message", code: "ERROR_CODE" }

## Do not modify
- database/migrations/ — ask me first before changing migrations
- .env file — never read or write secrets

## Common tasks
- "Add a route" → create in routes/, add handler in controllers/, add test in tests/
- "Fix a bug" → write a failing test first, then fix, then verify test passes

For a complete CLAUDE.md reference and advanced memory patterns, see the memory guide.

5 Beginner Projects to Build in Your First Week

Each project is designed to teach a different aspect of Claude Code. Start with #1 and work through them in order.

Common Beginner Mistakes (and How to Fix Them)

1. Skipping /plan before big changes

Mistake: "Refactor the entire auth module" → Claude rewrites 8 files in a direction you didn't want.
Fix: Always use /plan first. The plan is a proposal you control, not a commitment.

2. Not committing often enough

Mistake: Running a 2-hour session with no commits. Claude makes a mistake at the end, and you lose everything.
Fix: Every time your test suite goes green, commit. Takes 30 seconds and gives you unlimited rollback.

3. Pasting code instead of referencing paths

Mistake: "Here's my 300-line auth.js: [paste]..." → Context bloat, worse responses.
Fix: Say "Read src/auth.js and..." — Claude reads files directly. No pasting needed.

4. Asking for everything in one message

Mistake: "Add user authentication, email verification, password reset, and social login."
Fix: Break it into steps. Start with the smallest complete unit: "Add email/password login only." Build from there.

5. Ignoring failing tests

Mistake: "The tests are failing but let's move on."
Fix: Never move on with a red test suite. Ask Claude to fix the failure before continuing. Every ignored failure compounds.

6. No CLAUDE.md

Mistake: Re-explaining your stack and conventions at the start of every session.
Fix: 20 minutes setting up a CLAUDE.md saves hours across future sessions.

Next Steps After the Basics

Once you're comfortable with the first-session workflow, these guides cover the next level:

• Best Practices — CLAUDE.md structure, cost optimization, TDD patterns
• Development Workflow Guide — daily routine, git branching, PR review patterns
• Plan Mode — approve full implementation proposals before any code is written
• Complete Cheatsheet — every CLI flag, keyboard shortcut, slash command, and skill in one page
• Hooks — run shell commands automatically before/after Claude actions
• Prompt Library — 60+ copy-paste prompts for every common task
• MCP Servers — give Claude Code access to databases, browsers, and external APIs
• Sub-Agents — orchestrate parallel agents for complex, multi-step tasks
• Troubleshooting — fix auth errors, performance issues, and common session problems

FAQ

Related Guides

• Best Practices — CLAUDE.md, permissions, TDD, context, and cost
• Complete Cheatsheet — every CLI flag, shortcut, command, and skill
• Development Workflow Guide — daily routine, TDD, git branching, CI/CD
• Prompt Library — 60+ copy-paste prompts for every task type
• Troubleshooting — auth errors, performance, context, permissions
• Setup Guide — detailed platform-specific setup instructions
• All Claude Skills — full directory of Claude Code skills