I went through that stage in high school. I was always interested in girls, but was too shy to ask one out. I mostly just stared at them, hoping they'd get the hint. Apparently the vibe I was giving off was more of "I have an axe in my shed that I'd like to introduce you to." rather than "You're pretty. Would you go out with me?"

If I could go back and give myself advice it would be: don't put pressure on yourself. It isn't a race. If you don't have a girlfriend now, it doesn't mean you're an unlovable loser who will forever be a virgin, it just means you haven't found her yet. She's out there, probably feeling as shy and awkward as you are right now. Don't sweat it. Just be yourself. Also, don't stare at girls giving them the vibe that you want to invite them into your van in a dark alley. Don't do that. It really creeps them out.