Step 1 is to connect the workstation (the client) to the SQL Express or SQL Server.
Step 2 is to add in the Account(s) that had been set up in the SQL Express or SQL Server.
When you click on the blue File tab, if you only see the Sample account showing, click on File >New Account >Add an existing account. Click Next and the list of available databases will be displayed. Highlight each database to add (hold the Shift or CTRL key) and continue through the wizard until Finished. The software will ask you to exit the program and reopen to see the Account(s) added.