I just recently had a show, not my first, but my horses first show. He was fine when I was riding him, but when we were about to start showmanship, he wouldn't stop moving. Does anyone have any tips to help calm him down.
Well when we got there I lunged him and then tried to walk him around, then we went back to lunging and he was ok when we were by the trailer but as soon as we walked away he was antsy and wasn't quite sure of himself
Ah, I know this all too well. You will have to experiment with many different things- for some horses lunging takes off the edge and helps, but for others that movement can actually stimulate adrenaline and hype them up even more. Since lunging can be pretty mindless, it won't help your horse get his mind focused on you. Try taking him to a quieter area and practicing your pivots, backing, side passes, all things where he will have to stop and listen to you to do well. Don't get frustrated when he acts up though, because he will feed off it. Also, just calmly walking around to try and calm both of your nerves may help too.
Many horses will be calmer around the trailer, because that's most likely where all the familiar faces are. When you walk him away from the trailer, reassure him and give many pats, get a distance away, then make him stand. It may take him a few minutes, but the moment he stands quietly, even for a few breaths to begin, praise him and let him walk again. It's a form of pressure and release training that has helped my anxious horse at shows so much.
Take him to some fun shows just for the experience. When you get there, lead him away from the trailer. When he starts to get fidgety, practice your maneuvers. When he is being calm, just let him stand. I like hauling my youngsters to events we don't even compete in for just this reason. Pretty soon, he'll be acting like an old pro.