On iequine.com they are live streaming the classes going on. Right now they are starting with the novice amateur and youth working hunter, which is the entry level for the rider going on. This is followed by the Amateur working hunter and then the Senior Working Hunter, which has some of the top quarter horses competing with the trainers.
Tomorrow am is the inexperienced horses, the green and progressive classes, which is our first year and second year green. Except sometimes you will see some horses if not most do both their first year. Then there is the 5 yo and under horses WH, and some equitation o/f. There is a complete schedule on the AQHA Congress website.
Of note, even though this is aa championship show, you do not have to qualify, so you will see all levels there.