87 fourtrax 250 rear brakes locked up

I’m new to the forum and am just looking for any help I can. I’m not very mechanically inclined but am trying to get my quad going. The only thing holding me back now is that the rear brakes are locked up. The lever on the right is stuck in the down position and won’t move and the rear tires are locked. Hoping someone has any idea of what I can do to fix this. Thanks