Short answer: Log in to DirectAdmin, go to Advanced Features > SSH Keys, click Paste Key, and paste the contents of your public key file (the one ending in .pub) …
Short answer: Open a terminal (PowerShell on Windows, Terminal on macOS/Linux) and run ssh-keygen -t ed25519 -C “your_email@example.com”. Press Enter to accept the default file location, optionally set a passphrase, …