Go to the Auction and watch. Keep your mouth shut, eyes and ears open. Volume is going to be down right now but should be a good time to learn. Find the feedlot buyers, they'll be the ones on the front row that look most at home. They set the market price for the day.
Depending on what you plan on doing will dictate what class you buy into. Try to guess their weight as the day goes on. Then when you go back you should have a better idea of the process price and weight class.
Also if you can go to an auction on a weekday, the ones on the weekends you will be competing with hobby ranchers. Weekends may have more volume so pick your poison.