This can be a pain in the arse job if you have never removed a set of rear brakes before.
The cable should run from the handle inside the car back to the driver side drum brake system. You will see a funky end on the brake system that looks like what a bike would use only bigger.
So when you pull on the handle it locks the brake pads down good and tight. The pain in the arse part is feeding this sucker through the system and getting the brakes on or off. If you are lucky you will not need to remove the brakes, but you can never tell until you get that far along. It might not be a bad idea to take pictures so you can work your way back and maybe use the old cable to feed the other one into the same place would be a good idea. Duck tape might work well for that idea, no? Blah... I'm just babbling here.