Try some of these first:
Talk with your parents.
Talk with your friends.
Talk with a teacher.
Talk with another trusted adult.
Sometimes just talking through your problems can help alleviate some of your anxiety. You might even figure out how to solve a problem that's been bugging you by talking it through!
Do some breating excercises. Here's one you can try:
6. Who doesn't like to color? Grab a coloring book and go to town. They have all kinds of coloring books now, not just ones for little kids.
7. Try some of these calming websites:
Weavesilk -Draw some calming moving shapes
Rainy mood - relax to the sounds of a rainstorm