lapping heads

I recently bought a set of X heads, pulled of a running 340. they look great. I want to just put new valve springs, clean them up and lap the valves< I have never done this before. I can't afford to have this done professionally, although I know i should. Can anyon give me some advise on doing this> i will also put in new seals and locks. thanks for any advise, walt. :salut: