I need help with this girl?

Theres a girl who i really like for some reason. I'm not the kind of person that easily becomes infatuated with people but shes really different. My friends don't think shes "anything special" and I've only talked to her like once but i seriously want to get to know her better. The thing is I can be really reserved. I'm not a show off and I find over confidence a pretty unattractive quality. As a result of these things i have got into a habit of not going out of my way to talk to or flirt with girls even when i actually want to! There are things i want to say to her or show her but i cant bring myself to and what makes it worse is that every single time i see her shes with these two friends of hers who don't seem to like me very much. What the hell am i supposed to do! Shes completely outside my circle of friends (shes not even at my school) and i don't want to seem like a stalker or something lol. help!!!