How can i have more confidence in my self?

I'm shy and a little chubby. I want to join tennis and badminton at school. but i'm scared they will laugh at me because i'm chubby and i'm not so good a tennis. they will laugh( because i already get bullied at school). And when i have to read something out, at school like a presentation i get really nervous and can't read properly. and i dont walk with confidence i walk sloppy. I NEED HELP PLZ HELP ME!!!!