Advice on how to make friends at a new high school?

Freshman year I went to a freshmen campus (public school) then half of the kids go to each of the high schools. I went to one high school that next year for sopre year, then for junior year I went to a private catholic school. I made a lot of great friends. Now my dad is putting me in public school nbut its the second high school in the distrct I was in. I kinda have a image there at the school as the "rich private school kid" so not many people like me. So I guess the big question is how do I repai my image at the new high school and be able to make friends? Ill be a senior, in doing DECA, and a mentoring program, and my brother goes there. So how do I make friends? I mean I'm not ugly, I wear nice clothes I'm just shy...and people don't like me idk why!...so what should I do? Advice is appreciated! Thanks!