Edit or add an Alias (there are no pre-configured aliases on first start).
In the Alias configuration dialog choose the driver configuration for your database.
Enter the URL to your database. The URL format is database vendor specific.
If no user or password is entered SQuirreL will ask for it when a connection is opened.
Use the 'Test' button to see if your configuration works.
Double click an Alias to connect to your database. This will open a Session window.