To add a meeting room to your Google Calendar:

Click the plus sign next to "Add a Coworker's Calendar".

Now Click "Browse Resources" in the Menu that pops up.

click on the downward arrow on the site you would like to have your meeting add and check off the meeting rooms you are interested in.

You may find this can get overwhelming with all the calendar events, if that is the case you can select which Calendars are currently active by clearing the check boxes next to them.

If you would like to remove a Calendar from your Google Calendar just go back into the "browse resources" tab and clear off the check mark for the Calendar in question.