Nervous, shy, help! Please Answer immediatly!?

Everytime I go out in public I feel really nervous. I live on a busy street & when my mom tells me to take out the garbage I feel like everybody's looking at me and talking about me etc. And at school when a popular group of kids comes near me I get really NERVOUS & SHY. And when I sit in the school desk I feel all quiet and my hand shakes sometimes I try to be as still as possible. And I mumble alot more then I use to, so nobody can really hear me. And I just want to be normal and fit in with the regular kids. And also I can't look my teacher directly in the eye. Can somebody give me some advice! Because I'm going into high school in a month and I really need it to stop. Oh and can you guys give me some tips about being popular