Click on a time slot on the calendar. The default time frame for a meeting is one hour. You can also click and drag the time from top to bottom in this step.
Enter the information for the event.
Click "More Options".
From here you can be more specific about the time, repeating the event, the calendar on which it will appear (you can have multiple calendars), a description of the event, you can even add an attachment to the event.
Do NOT add a location a this will be added later.
Select the calendar on which you'd like to have this appear. (4th item down under Event Details)
Enter a description for the reservation. (Last item)
On the right side, "Guests" is selected by default. You can invite other people to attend the meeting if you'd like by entering their names and selecting the resulting accounts from the list.
To reserve a room, click "Rooms" in the same area as above. A list will appear with building abbreviations. Select the building and a list of the available rooms that you can reserve will appear. You can also see all rooms by changing the option at the top.
Select an available room and it will be added to the "Location" field on the left of the screen. (This looks like a map pin.) It will also be added to the "Guests" list below the list of rooms.
When you have completed your reservation, click "Save" at the top of the page. The reservation/meeting/event should be added to your calendar and the room will be reserved for you.