Rook and Pawn vs Rook is tricky.  The general rule is if the King who is trying to defend against the Rook and Pawn can get to the queening square, the game is drawn; if not, the game is lost.  Well, I prevented the King from getting to the queening square, but it was still drawn.  My center pawn wasn't advanced enough.   In the position, it is Black to move and draw. 

I think this is an instructive example.  Black can't let the pawn advance to his 3rd rank unless he's able to achieve that long side - short side defense.  For example, if black's rook had the long side (rook was on the a file) you could even give white the move and it's a draw eg

Therefore without this defense black has to prevent the pawn's advance which he does.  I really like his 2...Rb6

If white instead steps back and away on this first move, then such a defense is no longer necessary as the white king is out of play, and the pawn can be allowed to the 3rd rank eg

Move 3 is also noteworthy.  As Bill's variation on move 3 shows, the critical square is still e6.  And so again it's instructive for the same reasons -- because long side short side is impossible, black must be ready to combine on e6 with his king and rook -- this is why 3...Kg8 fails as black loses control of that square -- once the pawn advances black can resign... which is what we see in the main line when it advances black's pieces are ready and the draw becomes obvious.

i didnt get the point of this