Dear Big Will,
Don't be shy around her. Don't mope, don't look sad, don't look depressed around her. Don't seem unhappy. Most importantly, don't even try to figure her out. She's a girl. We are impossible to figure out
Be happy, act and walk and talk in a very confident manner. When you see her, say hi to her. Don't ignore her. Don't sound nervous either, even if you are. But before you start sharing your feelings with her, ask her to hang out first. Ask her to go grab some lunch with you afterschool, or hang out at the mall, or watch a movie. You don't have to make it seem like a date.
And if she's not dating anyone now, don't worry about what Chris or anyone else says. This is between YOU and HER. Don't let what anyone else tells you interfere with the way you act towards her.