Locate the slot (oval in shape) towards the bottom center of the brake backing plate. There might even be a plastic or rubber cap over it.
Get the brake tool from the parts store. It has a different angled bend on each end that gives you the leverage and clearence you'll need.
Insert, I think, the angled end into the slot. Lever the brake tool UP. This will bring the shoes in. The thumb wheel is really a multi-pointed star wheel. This is connected to threads that make the brake adjuster grow or contract. This pivots the shoes that are atteched to the backing plate.
Don't be afraid to mess with this awhile. You'll feel the movement. There is a joining spring that acts as a lock stop for the brake adjuster so the wheel won't turn freely, but kind of clicks as it goes around.
When you feel the you can't turn it any more, get a big ended punch or other blunt ended shaft that you can pound with a hammer. Tap this repeatedly all the way around the inside edge of the drum. At some point it will brake lose and begin to slide outwards.
