If you haven’t already, first follow the install guide to install the Focalboard server.
After installing the server, open a browser to the domain you used (or
http://localhost:8000 for local installs). You should be redirected to the login screen. Click the link to register a new user instead, and complete the registration.
The first user registration will always be permitted, but subsequent registrations will require an invite link which includes a code. You can invite additional users by clicking on your username in the top left, then selecting “Invite users”.
You are now ready to use Focalboard. Please refer to the user’s guide for details.