difficult to talk to guys?

[LMAO]

I go to an all girls private school and so I find it really difficult to talk to guys I have had guys try to talk to me but I am really shy...and whenever I go on a sports trip with them for school, I don't know what to say to them so I just plug in my earphones because I don't want it to be awkward. Whenever there is a dance, I am usually the one in the corner with a friend or two--sad, I know. There is this guy who also keeps stalking me--he saw my last name on the back of my hoodie, looked me up on facebook and I have seen him around when I go out shopping or something with my friends and I find it kind of creepy, even though he is kinda cute--he is like two years younger than me haha. and there are a couple guys I want to be friends with but a few other girls who just keep flirting like crazy
with both of them and I don't know how to talk to guys. I can be really quiet sometimes, but I am always honest and a lot of guys said that they think I'm pretty, but I don't know how to respond to comments like that so I just smile, say haha thanks and walk away lol. one guy thought I was really thoughtful so I said, how? and he comes up with a few examples and I said, haha that is sweet of you and walked away again....I just keep walking away because I am shy. I am 16 by the way, and I want to know how to be good friends with guys. I have two older brothers and play video games with them sometimes and I've gotten pretty good at battle field and COD (battle field is way better btw lol) but yea. What do you talk about with guys and how do you approach them?? thank youuu I reallly appreciate you guys reading this