How do I get into a relationship

Hi, so I'm currently in year 12 and there's this girl I've had my eye on for a while now, let's call her Josie, she's in the year below and I think she seems to be everything I want. There's just one problem: I get extremely nervous when I talk to people. I've never had a relationship before so Im really not sure how the whole 'courting' thing works now that Im not in primary school. So far the longest conversation we've had has been about glue, I don't even know if she has a boyfriend because we arent part of the same social groups at all (if you haven't already guessed I'm the quiet guy that sits at the back of a class not saying much to anyone and she's one of the more popular people). I would really appreciate any advice you could give because I really think I need experience of this sort of stuff before university.

Get talking to her. If it feels right, then casually mention going out. Go to a glue factory if you like.