There are many ways on how to start with a boy. Well I think that the best way is to be in one place with a boy and some other people. Like a classroom or a café with some people around to help you out. Now it is mostly always kind of scary to go and say hi, but you can go with some of your friends, just make sure they don't humiliating the boy or this could have a tough end. Wait for the moment when the boy is alone or only with 1-2 of his friends. Then you can simply start a chat. Now it may be a funny chat, it may even be a rude chat or something even more boyish. Don't worry, they won't start to like you just the second they see you, it takes time. After a while you should want until he is alone and start to talk normal, ask his MSN, e-mail or anything like that.
Chat, but don't chat too much. This could get the boy angry from countless messages that keep him from playing some game that drives him nuts. He can ask you out or you can ask him out for a date. Just don't call it a date. Just ask him out. By the time when you talk you should find out what does he like, what type he is: is he a computer geek (I mean pro) or does he like to work out and stuff. Then he should do the rest of the things. But there is 1 thing that is important. The 1st kiss. In the movies, the man always kisses a woman first. That is unrealistic. Actually I was afraid to do it too. And I didn't do it, because she did. That's right the girls see better when to kiss. And the have more courage in that, at least that's what I think. There could be a boy that would kiss you first, show him that you are ok with that, so he doesn't feel stupid.
A few pointers on how to know when is the right time: you constantly meet, hug and like to be close to each other. If you haven't kissed yet, do it. Remember do not try too hard on this, because bothering a boy isn't a good idea. Wait some time after a date to meet up again. After some time there is 1 thing you should know: Safety first! You don't want to be stuck with a baby don't you? Well I hope I helped you out a bit. Feel free to comment or ask some questions, I will gladly answer.