Anxiety about school.

So I'm starting seventh grade pretty soon and I was excited because I thought my electives we're gonna be fun and my type of style. however, I found out that I have art, a class that I don't know, foods, and group guitar. I'm also scared shitless because I got into excellerated math but there's a strong chance that my worst enemy will be in there too and I think I might get called on and get the answer wrong and he'll laugh at me. so my social anxiety has been the roof and school hasn't even started yet. I'm not worried about art or foods, but I'm worried about guitar class because ik nothing about the guitar but I keep on thinking that I'm gonna be the only one who's clueless.