To create new rooms or edit existing rooms:
Choose Content Management from the top menu bar
Select Room Bookings (this link may have a different name depending on your menu configuration)
To create a new room choose the + icon
To edit the settings for an existing room click the edit (pencil) icon
You can then assign the required Custom Fields to the room (refer article Custom Fields Global to create these) as well as the various settings for the room.
You can also configure the Opening days and times via the Open time link at the top of the page