Teach what?? Im guessing you mean PU

In that case, how did you learn it? Im sure however you learnt will be fairly transferrable to how your friend can learn.

Just remember that field experience is worth more than any ebook, cd, video ever will be. Also PU (for me at least) isnt about WHAT to do but more about WHAT NOT to do. Educate him on the behaviours and mindsets that have prevented him getting laid and the rest should take care of itself.