How can i get this girl? Please read?

Hey guys, i need some help with this girl. Alrite heres everything. Were juniors in HS. Friday is our last day before finals. This girl i've liked is really quiet and only talks to a few other girls. She doesnt talk to any other guy at all, NONE. shes really cute and i really like her. We've never had a ongoing full conversation before. So last friday, knowing the end of school is coming and being uncertain about us having classes next year, i decided to grow a pair. After the bell rang i walked up to her and said "hey {name}, i know we never really talked, but i was wondering if you were doing anything this weekend." she said "Oh, yea.....sorry" and walked away. I felt like trash the entire weekend until i learned she actually did go somewhere with her family. Tomorrow is last day of school before finals. Today i wanted to go up to her and talk about the weateher or sumthing but it seemed as if she avoided eye contact with me. I walked into last period a little late, and normally i would see her first in class room(shes like 4-5th row first seat) but the very second she saw me she looked away and when the teacher started to hand out papers(i sit 2desks behind her but kid in front of me was absent) she didnt even turn around to hand it to me or collect later on, just put her arm behind. All honesty here, i'm not a bad looking guy. To validate that i got a 8.0 on anaface(rates you 1-10) and im 6'1" 180lbs but really cut(i worked out for 2years have noticeable 6pack etc). Like, not being a d0uche here but she doesnt talk to any guys, why wouldn't she want to if a guy shows intrest in her. Please help me. I REALLY REALLY like her. I even just considered msging her on facebook in the summer just saying how i feel about her but i dont wanna creep her out. PLEASE HELP ME!!!