Virtual Secretary checks everyone's calendar including the room's calendar.  Typically one person will have a schedule of all the rooms.  On that schedule you need to block out times when the room is not available.  As an example, see the schedule below for one of the rooms where I teach.



The blocks of time were created by just clicking and sweeping down the mouse for each time.  There is no need to name the event.  After you create it you should set it to repeat so you don't have to do that more than once.  (of course if the schedule changes every week you will need to deal with that.)