On your computer, open Google Calendar (https://calendar.google.com). Create a new event or open an existing one. On the right side of the page, click Rooms. Click a resource you want to add. Click Save.
More information here: https://support.google.com/calendar/answer/143753
If the room is not available to select while creating an event this means that the theater is already scheduled for that time. You may view the full room calendar to see who has the room to see if you can share the space. You may also use the 'Find a Time’ tab to see room availability.
If you want to see what other activities are scheduled in the shared spaces you can preview the shared calendar for that space. To do this:
Log into Gmail and select “Calendar” from the Apps box in the upper right hand corner. Click the arrow next to “add a co-workers calendar”. Select Browse Resources Select the room (ex: VHS Theater) and click the “preview” icon.
You may also check the VHS Theater calendar from this link.