i like this girl who has become a friend but she has a boyfriend what should I do?

get her

Because she is your friend and already has a boyfriend, there is not too much you can do. You do not want to step on her boyfriends toes, then that will be disrespectful. Since she is your friend just remain being friends with her. The both of you can still keep in contact while you are away (talk on phone, write letters). But you should not pursue the relationship any further. Just think about it like this...how would you feel if your girlfriend has a male friend and he likes her, he tells her, then he tries to make a move with her? You may not like that.
If you are a friend to her the best thing to do is just stay friends and do not involve yourself in her and her boyfriends relationship

Um, tell her to put you on her waiting list? =p

Talk to her. Or wait 'till she breaks up with her boyfriend.

Tell her how you feel it won't hurt you.

If she has a bf, then it's the right person at the wrong time. Move on.

Like you said she is a friend leave it at that. how would you feel if the shoe was on the other foot and you were the boyfriend and some one was trying to get your girl.