I really like this guy but I don't know how to tell him because he doesn't like me i don't think, what do I do?

I was in the same boat ;)

Here is what I did...

There was this guy I sorta liked, but he was a good friend of mine. I didn't like him enough to date him, so you and I differ in that. Well, I casually told him I liked him.

By casually, I mean you should bring it up in a conversation, almost like it doesn't faze you. Bringing it up casually would be saying, for example, "that is why I like you." If he says he just wants to be your friend, don't fight him or you will lose a friend. If he only sees you as a friend tell him you told him out of respect because you feel the same :p

You want to scare him off  and damage your ego, then tell him now how you feel or try to be friends first and let him figure things out by himself so be patient as this could take a guy a little time to get.  So again, be friends first and then let Nature do its thing.  Good luck