GIRLS I REALLY NEED ADVICE?

Well I like this really cute girl at school I know we have a lot of the same interests like music and john Mayer especially well I'm gonna be a junior anyways and I have a few dilemmas she's really smart and I'm not the most studious person but I try. And she has a bf but they have an odd relationship like sometimes they dnt even say hi. And also I'm really shy I write music and play guitar a lot. And also I volunteered to play guitar for a mass and she's in choir and she kept looking back at me during readings and stuff. She's really cute and I'm not bad looking. U can check my pulse for pics if u want. Well anyways how can I break the ice and talk to her she always looks at me in the halls and stuff but I nvr say a thing. And its summer too. So I might need tips oh and she doesn't party drink hook up. Nor do I. So yeah any tips I rly like her and I can't intro my self cause we had a one semester class.