Getting a girl I like? Advice?

Okay, so im in 8th grade, im 14. Im a 'popular' kid at my school, and all my best friends have GFs. One of my friends is a , Wyatt. He goes out with girls and dumps them and breaks there heart because he feels like it, but then girls give into him when he asks them out again. Another friend i have has been going out with the same girl for maybe a year? Shes a but he isnt, but they make out all the time. Another friend i have is very chubby, but he gets hott girls all the time. He treats them good, but how does he get them? Im not a man , im not fat, and every time i get a GF we stay in a relationship for 1 year at the minimum. I actually talk to them and call them back etc. My friends tell me to just act like them and go out with a girl for a week then your done. Alot of girls like my right now, but i dont like them. I like on in particular and her name is Emma. Of course wyatt went out with her once, but she isnt a . Wyatt tries to get me to not like the 'crusty' emma, but i like her. My older sister in 12th grade knows emmas sister in 12th grade. Emma is really pretty and really cool to talk to. When i first met her she was flirting with me and would 'fall' on me on accident, and walked with me everywhere. But now she says im her best guy friend and shes dating a guy the she finds really annoying and im not sure if they will last a while. How can I get her to like me? Shes in the 7th grade and i dont see her much in school, only between cles. I need advice?