Polish friend travelling to the u.s

Hello!
I have a friend that wants to come visit me here in the u.s. I was wondering if anyone could tell me what he needs in order to get here. I know its kind of a tricky process and I dont want something to go wrong for him when he getting his visa and stuff.

Any info would be greatly appreciated!Thanks:)

Try here:

poland.usembassy.gov/poland/consular_faq.html