From the Dashboard, after logging in:
SecurityGateway will then give a status-report of the number of lines scanned from the file, number of items successfully imported, and number of items that failed.
Note that the CSV file needs the following format to be successfully imported:
Domain, 'MaxUsers'
Under Domain, put in the name of the domain you wish to import, and the maximum amount of users you wish to configure for that domain under 'MaxUsers'
Additional Notes:
Any imported domains will use the default user-verification sources you have setup, unless you specifically specify one for that domain. You may do so by editing the domain under Domains / Users and selecting a specific verification source from the list at the bottom of the pop-up window.