Checking a bag is easy. It's treated just like any other non-rev bag. Just go to the ticket counter and ask to list for the Jumpseat. They'll tag your bag to abd check it. Then go to the gate and check in again. You may or may not have to fill out a form. Sometimes they put a standby tag on checked bags and sometimes they don't. I would plan on your bag going if you don't get on. If you don't get on just wait for the next flight.