BMW 720i rear bumper removal

I need to take the rear bumper off of a BMW 720i. I'm not sure how to go about this and need some guidance. It will have to go back on, so I can't just break it off and that's not a good idea anyway. I'm sorry but I don't know the year so I just put 1977 because it was the year the E23 series came out (the car doesn't look that old). If you need pictures there are a couple at CarDatabase.net, but these aren't very helpful to me. According to chacha.com the mileage is 15mpg city and 22 mpg highway. I can go look at the owner's manual again on Monday, but it is in German. I will try to provide any more information you may need on this car, but some of it might have to wait until Monday.