Pick a small folder for your first session
Your first Claude Code session should end with one change you understand, not a rewritten application. Claude Code runs in your terminal: it can inspect project files, suggest edits, and run commands within its permission settings. Think of it as a coding assistant working inside a folder you choose.
Start with a disposable project or a clean copy of an existing repository. Avoid your home directory, which may contain unrelated documents and credentials. If you already have a project, check its README for required tools before asking the assistant to run anything.
The commands below use Bash on macOS or Linux, including a Linux environment through Windows Subsystem for Linux. Windows PowerShell uses different installation and environment-variable syntax; do not paste these Bash commands into it.
Install Claude Code and check the terminal
Open a terminal and confirm that you are comfortable finding your current directory with pwd and listing its files with ls. You do not need to become a shell expert, but you should know which folder a command will affect.
Use the official Claude Code installation instructions for your operating system. On macOS and Linux, the native installer command is:
curl -fsSL https://claude.ai/install.sh | bash
This downloads and executes an installation script. Verify the address against the official documentation before running it, especially if you copied the command from somewhere unfamiliar. If curl is missing, install it through your operating system's package manager first.
After installation, run claude --version. If the terminal cannot find claude, reopen the terminal and check the installer's PATH instructions. PATH is simply the list of locations your shell searches for programs.
Connect SwiftRelay without exposing your key
Claude Code needs authentication before it can contact a model. SwiftRelay is a practical option when you want token-based billing and one relay account for your development tools. Sign up for SwiftRelay, collect the small gift credit available to new accounts, and create an API key in your account dashboard.
For this Bash session, set the relay address:
export ANTHROPIC_BASE_URL=https://api.fastapirelay.com
Use the bare host here, without /v1. Claude Code and OpenAI-compatible SDKs do not use the same base-address convention.
To enter the key without placing its value directly in a shell command, run these two commands separately:
read -s -p 'SwiftRelay API key: ' ANTHROPIC_AUTH_TOKEN; echo
export ANTHROPIC_AUTH_TOKEN
The first command hides your input; the second makes the value available to Claude Code. These settings last only for this terminal session. Do not put the key in project files, commit it to Git, or paste it into an assistant conversation. If authentication behaves unexpectedly, check for older credentials or conflicting environment settings.
Ask for an inspection before an edit
Change into your chosen project directory and run claude. Follow any startup prompts carefully. If asked whether to trust the folder, approve only a directory whose contents you recognize.
Use this as your first request: “Inspect this project and explain its purpose, entry point, and available test commands. Do not edit files or run installation commands yet.”
This separates understanding from action. If you choose a model such as Claude Sonnet 5.5, use the exact model identifier documented by SwiftRelay rather than guessing an API identifier from its display name.
Make one change and review the result
Next, request a bounded task: “Add one test for this existing function. Explain your plan first, change only the necessary files, and ask before installing dependencies.” Review permission requests instead of approving everything automatically.
- Read the proposed file changes and confirm that they match your request.
- Run the relevant test command after checking what it does.
- If the project uses Git, inspect git diff before committing.
- Check SwiftRelay usage afterward so you understand the token cost.
A good first lap leaves you with working authentication, a familiar permission flow, and one understandable change. Save larger refactors for after that foundation is solid.