how to backup file folders

I would like to create a backup of file folders. unfortunately it seems that I can only create backups of partitions. The reason I would like to create a backup of file folders is because I would like to create a shortcut on my desktop to backup just those file folders.
The reason I need this is because I have a customer who will only be connected to an external backup drive at night and he needs to backup just his documents directories. I was hoping non-stop backup would do the trick but it doesn't. With non-stop backup it detects that the external drive has been disconnected and it also detects that it has be re-connected. But when it detects that the drive is re-connected it does not check to see if any of the files in the directories have been updated. Too bad I cannot create a shortcut for non-stop to indicate to check for updated versions.
so..... is there any way I can perform a backup of file folders that can then allow me to create a desktop shortcut? Or is there a way to tell non-stop backup to check for revisions when a backup drive is re-connected?

I already sold the customer on the idea before I confirmed it could be done, silly me!

thanks for the help

john