Hi,
Just wanted to put in my 2 cents...
I noticed that you're currently in Farminton, MN. There are a couple of senior corps in the area. Chops, inc. and Minnesota Brass. I'd suggest that you and your band director and your friends who are as interested as you are, go check them out. Summer is the hieght of Corps season. Go check out rehearsals, take notes. Shows and competitions are very intense.
I lived in MN for a while. There is an Independent Winter Guard in the area. I don't remember what they are called anymore, but there is one around. Check in to that too.
If you are starting something at your school like a Winter Guard or something, start small and slowly. Get as much help as you can.
Hope that helps... :)