When creating an event/meeting on your calendar, you can invite others to attend and reserve rooms at the same time.
Open Google Calendar
Click on the Day/Time that you want your event/meeting to be held
When the Event Details window pops up, click the More Options button
In the Event details page, find the Add section and click Guests.
Type the first few letters of a person’s name or email address in the box. Matching addresses in our directory appear as you type.
Click one of the suggestions to add that person to the event. If no suggestions appear, type your guest’s full email address and click Add.
To reserve a room for your meeting:
In the Event details page, find the Add section and click Rooms, etc.
(Optional) To see only available resources, check Show only available.