How can I get him to notice me?

There are a couple of things you could do
First,
Find something outside of school that you could meet him at. Any activities, sports or community involvement that he is involved in could get you to know him better.

Second,
Start an online friendship. Find out if he is an online fellow and get his Facebook or Myspace or AIM and begin chatting with him on there. It can work wonders to keep communication open. Don't let the online security suck you into believing that there is some kind of mutual crush, but let that play out.

Third,
Talk to him. Engage him in conversation and just be more outgoing with him. He can't know who you are if you never contact him. Feel free to just chat with him when you see him and try to see him often. Even in large schools, there are usually only a few lunch periods, try to use those.
Also, Games, dances, assemblies, and other mass gatherings would be a great way to do this, just plop yourself down near him.

Fourth,
If you really like him, feel free to ask him out. There is a risk involved, but the benefits are well worth it. The worst thing that happens is that he says "No" and you have your little heart broken for a few weeks before you move on. Seriously consider trying this. It is only a little bit uncommon, and if you sit and wait for him to come to you, it is more likely than not that nothing will happen.

Fifth,
Become friends with some of the people he hangs with. Mere association with them can connect you two at social functions.

well first do you both have a myspace.?