Install Claude Code, sign in, and run your first session inside a real project. This is the workspace every other lesson builds on.
Why: Claude Code is a terminal tool — you install it once, then run it inside any project folder. When: use the native installer, or npm if you already have Node. Where: it works on macOS, Linux, and Windows (WSL recommended on Windows).
# Native installer (macOS / Linux / WSL)
curl -fsSL https://claude.com/install.sh | bash
# Or with npm (needs Node 18+)
npm install -g @anthropic-ai/claude-code
claude --versionWhy: Claude Code works on the files in your current directory, so always launch it from inside a project. When: the first run prompts you to log in with your Claude account or an API key. Where: cd into a real git repo so you can see it make and track changes.
cd my-project # a real project you can experiment in
claude # launches the interactive session; sign in when asked
# Then just talk to it:
# > what does this project do?
# > add a health-check endpoint and a test for itWhy: these built-in commands confirm everything is wired up before you go further. When: run /status anytime something feels off — it shows your account, model, and working directory. Where: /doctor diagnoses installation and config problems.
# Type these at the Claude Code prompt (not your shell):
/status # account, model, working directory, MCP servers
/doctor # diagnose install / config issues
/help # list every command