I would suggest finding a trainer in your area who shows in AQHA. That way he/she can explain and teach you what is required. If you find a trainer, ask to go with them to a few AQHA shows and watch other riders showing. If your trainer can, have him/her explain to you what is going on in each class, that way you will get a better understanding of what is happening.
And I agree, before you step out into a breed show like an AQHA show, it would not hurt to gain exprience through open or 4-H shows first.
KEEP HORSES IN THE STABLE & OFF THE TABLE !!!!! ♥♥♥