Count yourself lucky you're not dealing with adult relationships yet. They're a right barrel of laughs... NOOT!. As for advice, well I was in the same situation when I was in school. Didn't help that I was fairly overweight so naturally I didn't think any girls would be interested, and i'd be right anyway they weren't. I know how hard that first step is though even if most people on here don't. I gained my confidence through getting fit and making myself feel better. Just be proud of who you are and find something good and unique about yourself no one else has. If you get an opportunity to talk to this girl take it. If you get rejected it's not the end of the world, it's life and it happens.