Paris,
Let me get on my soap box for just a second... If you just got into herps, I find it odd that you're already looking into selling at expos. I know that I personally try to keep a type of animal for about a year before I begin trying to breed them. This way, you get to see a good bit of life cycle (assuming you start baby or juvi) and you can determine if it's an animal that you really want to have. I know I was very thankful I had this "rule" for myself when I owned crested geckos. They are super cute animals, make wonderful pets, but it would have driven me insane to have had lots of tiny, sticky toed geckos in the house. They just weren't for me. Also, I don't ever think it's a good idea to get into animals for money. You need to have a genuine love for the animals you're breeding (another reason to keep them for a while to make sure you really do think they're super). I know quite a few people (including myself) kept some sort of herp, got a few more, made a few babies, got a few more, and then decided to officially go into breeding so that you didn't turn into the Crazy Lizard/Snake Person. I just ended up having so many leos that I decided to become an "official" breeder. I knew I couldn't keep all the babies, and would be selling them, so why not have a name to do it under? Since then I've gotten much more serious about the business aspect of it, but it started as and will always focus on a love of animals.
*kicks soap box to the side and stand on the ground again*
As for finding out about how to get into expos... Just go to the websites. There's almost always information and a form there. Usually you just print, fill, and mail. Everything you need will come back via snail mail or you'll get it when you arrive.
Sorry for the lecture, but I find that most people who get into this for the money, leave disappointed and with suffering animals. I hope I have it all wrong with you.
Good luck,
Erin