Undecided Question

How to be cool and confident?

I'm going back to high school soon. 9th grade, and I am very nervous.. I feel like my stomach is falling out of my butt. I'm not confident what so ever. I have scoliosis and a big nose.. and don't know what to say to you kids.. -.- Why do you guys pick on other kids and make them feel like crap? :( (im not saying you all do that.. just the mean ones out there.) WHAT THE HELL DO YOU WANT FROM ME?! *head desk* Erhm.. anyway. o.o How do I feel comfortable in my own skin and not care what other idiots say?