You like this guy and he does not know you like him what do you do?

okay , im no expert but if he's a friendly person i think you should try to develop a good friendship with him before you tell him. and if you are too shy to tell him try the occassional 'hi' and smile to break the ice.

you can also try to make him laugh, everyone appreciates a good laugh now and then

just don't completely avoid him, i made that mistake, and I'll never do it again!!