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Tutorial··4 min read

Claude Code complete beginner's guide: set up, first project, real tips

Everything you need to get Claude Code running on your machine, understand what it can actually do, and avoid common first-week mistakes.

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Claude Code complete beginner's guide: set up, first project, real tips

Claude Code is Anthropic's official terminal-based AI coding agent. Unlike ChatGPT or Claude.ai, it runs directly in your project folder — it reads your files, writes code, runs tests, and executes shell commands on your behalf. This guide gets you productive from zero.

What Claude Code actually is

Most "AI coding tools" are glorified autocomplete. Claude Code is different in one key way: it has agency. When you say "add a dark mode toggle to my React app", it doesn't just suggest code — it reads your existing components, finds the right file, writes the change, and runs your linter to verify it compiles. You approve each step or let it run autonomously.

The mental model shift: Claude Code is more like a junior engineer who can read and write every file in your repo than an autocomplete system that finishes your current line.

What you need before starting

  • A Claude Pro, Max, Team, or Enterprise plan, or a Claude Console account (the free claude.ai plan doesn't include Claude Code)
  • A terminal you're comfortable with (macOS Terminal, Windows Terminal, iTerm2 — any of them work)
  • A project to work on (new or existing — both work fine)

Installation (one command)

On macOS, Linux, or WSL:

bash
curl -fsSL https://claude.ai/install.sh | bash

On Windows, in PowerShell:

powershell
irm https://claude.ai/install.ps1 | iex

Verify it's working:

bash
claude --version

The first time you run claude, it asks you to log in through your browser. Your credentials are stored, so you only do this once.

Your first session

Navigate to a project folder and run:

bash
cd my-project
claude

Claude Code reads your project files as it needs them, so you don't have to paste in context. Try:

what does this project do?

It will read your files and explain the codebase back to you — surprisingly useful for jumping into an unfamiliar repo.

Now try something real:

add form validation to the signup form. use zod. show me what you're planning before you make changes.

The "show me what you're planning" instruction is one of the most important habits to build. Claude Code will explain its approach in plain English before touching a single file. You catch bad assumptions early, before they become wrong diffs.

The five commands you'll use every day

  1. claude — start an interactive session in the current directory
  2. claude -p "your task here" — run a one-off task, print the result, and exit
  3. claude --continue — resume the last session (useful for multi-step work)
  4. /clear — clear conversation history within a session (frees context for a new task)
  5. /context — see what's filling the context window

Understanding context windows

Claude Code's biggest practical limit is context. Each model has a fixed context window, and on a large codebase it fills fast. When context gets full:

  • Older parts of the conversation get summarised (compacted) to free space
  • The agent may miss details from earlier in the session
  • Long sessions degrade in quality

The fix: break big tasks into small sessions. "Add auth" is a bad session. "Add the Supabase client setup" → new session → "Add the sign-in page" → new session → "Add the protected route wrapper" is a good pattern.

Skills: the feature most beginners miss

Skills are reusable context files (SKILL.md) that you install once and activate in every relevant session. They're the difference between starting from scratch every time and having Claude Code already know your tech stack.

Install a skill by downloading its SKILL.md into your personal skills folder:

bash
curl -fsSL --create-dirs -o ~/.claude/skills/nextjs-app-router-pro/SKILL.md https://claudeskil.com/skills/nextjs-app-router-pro/SKILL.md

Now, whenever you ask Claude Code for Next.js work that matches the skill's description, it loads the skill's patterns — App Router, Server Components, the works. No re-explaining. You can also run it directly by typing /nextjs-app-router-pro.

Browse about 200 skills at claudeskil.com/explore.

Common beginner mistakes

  1. Tasks that are too vague. "Make this better" gets mediocre results. "Refactor this function to use early returns, add JSDoc, and add a unit test" gets great results.

  2. Not reviewing diffs. Claude Code will tell you what it changed — read every diff before approving, especially on business logic. The agent is fast but not infallible.

  3. Running in a directory with no context. Always run claude from inside the project folder. The agent works in the folder you start it from — if you run it from ~ it has almost nothing to work with.

  4. Using it only for new code. The real power is on existing code: "explain this function", "why does this test fail", "what would break if I changed this type". Those tasks are hard for a human to do quickly and trivial for the agent.

A practical first week plan

Day 1: Install, run in one project, ask it to explain the codebase. Day 2: Ask it to fix a real (small) bug you've been putting off. Day 3: Install one skill that matches your main tech stack. Day 4: Use it to write a component or API route from scratch. Review the diff carefully. Day 5: Try auto mode on a task you're comfortable with, let it run, see what it produces.

By the end of the week you'll have a strong intuition for where the agent shines (refactoring, explanation, boilerplate) and where it needs supervision (complex business logic, auth, migrations).

Where to go next

  • The full docs: claudeskil.com/docs
  • Browse skills by your stack: claudeskil.com/categories
  • The Anthropic Claude Code docs: code.claude.com/docs

If you get stuck, the agent itself is usually good at explaining why something went wrong — asking it "why did that fail?" is often faster than a Google search.