Also, there is a rubber plug on the back side of the brake. Pull that out and stick a long flat tip screwdriver through. You should feel a little gear with teeth that you want to turn to loosen the rear brakes. That is the slack adjuster. Turning it up from the back side will make your brakes looser. When you put your drum back on, you will want to work your brakes several times to re-adjust your rear brakes.
Then like the last poster said, tap around the outside edge of the drum to get it off, penetrating oil around the hub. 3 lb hammer works great for knocking the old studs out the back of the hub.