Rear Break Drum Broken? How do you get it off

1999 Ford Taurus, 143000miles

I was backing out of my drive way yesterday, when all of a sudden my car stopped backing up. Got out had boyfriend try to back it out and rear passanger tire would not move. Took tire off and figured that one of the break pads broke off inside the drum. Problem is we cant get the drum off of the car. Read the chilton manual, followed the directions and still cant get it off, any help would be greatly appreciated.