The brakes can be adjusted from the back. There are two large nuts with small studs sticking out of the center of them. You will need a 9/16 and 1/4 inch wrenches. Using the 1/4, place it on the small stud and then using the 9/16, loosen the large nut. Then turn the small stud towards the center of the wheel. This will back off the brake shoes. Do this for both large nuts.
This might loosen the brake enough to allow the car to move...however...the issue is probably due to the wheel cylinder going bad. When they do, the cylinder pistons tend to push out and lock the shoes to the drum. At that point, the only fix is to remove the drum and either replace the wheel cylinder or rebuild it.
The drum comes off by removing the center cap, cotter pin and large nut. The drum and bearings will then come off of the spindle. Be careful not to score any of the bearing surfaces.
Hope this helps!