When creating an event in Google Calendar through the Create button, you can book Google rooms/resources:

1. Add event date and time  
2. Access resources by selecting Rooms on the right side and a list of resources will display
3. Scroll through the list selecting items to expand or type the resource or building name into the Search rooms box to find the desired resource. (By default, only the resources that you have access to book and that are available at the requested time display.) To view other date/times options, view calendars' availability
4. Select the desired room to add it to the list of Participants below
5. The resource is also automatically added to the Where field as the location
   
6. Select Save and as long as the resource is available and you have access to book it, it will be booked