Ruy Lopez Exchange variation end game

I worked last night with a USCF 2000 level player. He has been helping me with the Caro-Kann. I mentioned in our last CK session that I was going to take up the Ruy Lopez Exchange Variation and he said he played it as well. Last night he quizzed me on the basic ending of the Ruy Lopez exchange.

The basics steps to this are:

1. centralize the king
2. build queen side pawn wedge (a3,b2,c3 or a4,b3,c4)
3. Create passer on the king side

want to practice try here

Some of the ways of breaking through are/were not so obvious to me so I am going to create some puzzles here and some example games to show the ideas...
still under construction
--- break through key puzzles