Get help.

You aren't going to get anywhere if you don't understand the material. If you don't get something, go to the teacher before of after school to get help. I know it can be scary, but it really does help. 

If you ARE too afraid to have a one on one study session with your teacher then ask a friend to go with you. Or you could kick the teacher out of the whole picture and just go to a friend who knows what's going on in the class. If you're like me, and study at super late hours of the night when NO ONE'S awake, you can visit teaching websites. These websites have actual teachers and college professors that explain material step by step with videos of them actually showing how they get from one point to the other. One website that I use for math help is http://www.khanacademy.org/

This site is AMAZING. like really. use it. create a user account (it's free) and go at it :)

Moral of the story...GET HELP!