Girl i like should i message her on fb?

alright, so theres this girl in my school, shes a grade below me, (where both in high school) and the only class i have with her is gym. She seems really nice and pretty and i like her, but im not friends wit any of her friends and i dont think she is with any of mine lol. evreytime i see her shes usually with her friends smiling, and laughing, (in gym too wit a few pple lol) so she seems really nice and all, im nice too, and sweet but theres one thign, i never talked to too many girls, i used 2 be a qiuet kid but still now i only talk 2 a few girls. So yeah weve never spoke before weve looked at each other in the halls (still do at times). I also hear shes smart and talented (shes in the school choir), were friends on facebook btw...so what should i do...i really wanna meet her,lol tht sounds kinda creepy if i do that...i knw her name but idk if she knows mine lol (she probably does but idk and idt she does) so i wanna get to meet her what should i do? im a lil scared to like message her...because im afraid ill sound creepy.. but what should i say when i message her...and tomorrows the last day of school... my best friend said i shud do it tonight....guys please help and thank you for helping...