The first thing you need to do is determine what kind of showing you want to do and then you can go from there. I assume you want to do showmanship? You need to practice a lot, especially on walking a straight line. Your horse needs to be able to trot in hand, pivot, turn, lead well, and listen to your commands. Try watching videos on Youtube to get an idea of how it should look.
Become a member of the state club for your breed affiliation. Get involved in their activities. Now is a great time to do that...a lot of times there will be clinics & other offerings during the winter months.