Backing up Microsoft SQL databases for backup is straightforward. If you manually select the .MDF and .LDF database files, the WholesaleBackup client will automatically use the SQL Server VSS writer to back up the databases.
You can also open the client, and then on the Backup->Selections tab open the tree browser for "VSS System Components" and, after the GUI has loaded (which may take several minutes), select the "SQL Server Writer" in the right hand pane.
If you double click on "SQL Server Writer" in the right pane you'll see precisely which databases will be selected to backup. If you only wish to back up selected databases from this list, you can manually select them. Or if you wish to exclude certain databases, make sure they have a red "X" beside them.