Friend who is depressed, what do I do?

I have a friend that i met about a month ago, and he suffers from depression. I want to help him somehow but I just dont kow how. Today he wanted to hang out and i was with a friend down at the quad, but i said he could come and he did. he came and idnt say much even when i asked him stuff, then all of a sudden he just walked off. I texted him and he said he felt like crap and that wasnt helping him. I invited him to a moie the other day and he said he would go but now he says we will see. What can I do for him??? plese help!