You can use the Import/Export feature in your Web Control Panel at net.brosix.com. The import process is explained in details in the Web Control Panel.
Here are details how to export user accounts from an Active Directory:
https://help.brosix.com/export-active-directory-users-into-a-csv-file/
You can also use Brosix LDAP Sync Tool to automatically sync your Active Directory with your Brosix IM network.
The Web Control Panel is available only in Brosix Enterprise.