Just go to the track and get a few practice sessions under your belt. Learn the track and the car. Then if you want to race enter the novice class, sometimes called sportsman class. This is basically a beginners class and will usually consist of alot of diffrent types of rc cars and trucks. If you like it, rather than upgrading the Hornet (which is an old school 30 year old design that was re-released) I would suggest getting something from Team Associated, Losi, or Traxxas depending on the class you want to run.
Right now Short Course trucks are all the rage. The most popular begginers truck is the Traxxas Slash. I personally prefer the Team Associated SC10 which is also available in a ready to run kit (RTR). Depending on your budget and funds I would maybe pick up a new ready to run kit, or check the for sale section here and get a good deal on a slightly used set up.