What should i do about my new friend?... i really wanna help him.?

It's good that you want to help this guy, but I'm just warning you be careful, If I was you I would talk to your pastor, ask everybody to pray for him and you can pray for him too, it's good that he said he will come to your church, just try to explain to people there why he is going there in as few words as possible so nobody is offended or embarred, have him take to the school counselor (I'm sure your school has one) but if not then I think it would be nice if you helped him find one, also I think it would be nice if you talked to your parents about it, they might have some helpful suggestions. Try to help him be happy besides him using pills, help him find a hobby that can help him get his mind off depressing thoughts. Tell him that praying can help him be happy, that God can be his friend for the asking and that cutting or whatever else he's doing doesn't make him happy but sad. Hope This Helps!