Help! i just wanna be friends!

All you have to do, is tell him the thruth, but in a not to hard way. You have to explaine to him that alto he is sweet and great and all, you just don't feel atracted to him somewhy. He should understand.
Remember. "The tongue has no bones, yet it breaks bones." Meaning, carefull with how you say what you want to say. Be gentle with the words.
Good luck
Later
Tim