Main fing when playing "''Tap" guitar right, is to turn your amp up to 11.
Youtube Nigel Tuffnel, if you haven't seen Spinal Tap. Very funny.
If you mean fingertapping, it is really just doing hammer ons and pull-offs using your right hand as well as your left. For instance, you couldn't hammer on from the 5th to the 17th fret simply because your left hand can't stretch that far. So you use a finger from your right hand to do it.
As others have said, there are lots of lessons online for free.
In the same way that you can do pull-offs using all fingers on your left hand, you can do the same techniques with your right hand. Youtube is full of show-offs 8 finger tapping. Unless it is musical I don't like it. There is someone on here who I think would be a great tapper, though.