After starting Code-Navigator the Database Connections Dialog popups on the screen. It allows you to add, edit and remove connections. Just now only mySQL is currently supported.

If you have started the dialog for the first time, just click the "Add" button to add the database connection you have predefined for Code-Navigator RDBMS tables.

If you want to add or edit a connection the dialog below pops up on the screen. The connection string is usually based on the real of the underlying RDBMS system.

You should continue with the main window.