Don't listen to Chunsoo.. If it sounds like fun you should look into it. It could be a really great experience.
Back when I was your age... Geeze I sound OLD... Anyway, when I was in High School they had the McDonalds HS Marching Band. Kids from every state in the US.
I always wanted to audition, but couldn't afford the travel expenses. In retrospect I'm glad that I didn't. The uniforms were freakin' BUTT UGLY.
I did get accepted into the Lions Club All-State Band for Michigan in 1979. We marched in the parade for the Lions Club National Convention in Montreal Canada. It was one of the best 'musical' experiences I've ever had. So many good players, so many really nice people, and the uniform wasn't ugly!