I remember hearing IM Danny say the Rook endgames are know to be very drawish even if one side is up a pawn. 

How is this possible and can someone explain to me were I went wrong in the following game?

For one thing your play with your rook was very passive.  You just moved back and forth on the d-file.  You need to seek open files for your rook and get behind the enemy pawns where a rook can rack havoc attacking the pawns and checking the king whenever he tries to advance.

Hi Pascalz.  45 h5 is better than 45 Kc3 so your opponent's king does not make into your territory. 

Black really enjoyed losing opening tempo with that Queen, huh? 

You really have to experience trying to win every game of chess no matter if experts say that positions are drawing, or drawish. It's hard to understand that rook games are drawn until you keep trying to win them. So, much experience is necessary in order for chess players to learn about how to draw with rooks or opposing-coloured bishops, in my tiny opinion. I don't know how many times my opponent will type that we have a drawn position, but I type that I want to continue, then they lose, or I lose. So play to the end until it's easy for you to draw, or make sure they know how to draw

The big secret to Rook endings is just this: active Rooks rule, passive Rooks drool.

Try 48 Rf2 instead.  If ...Kxh4 49 Rxf6 Rxe4 50 d6 exd6 51 Rxd6 and\the outside passed b-pawn wins, or 48 ...Kg6  49 Rg2+ Kh5 (49 ...Kf7?  50 Rg4 followed by h4-h5-h6 etc)  50 Rc7

The rook looked very passive on f5. I don't know why you even played Bc6?

40.b3 + exchange wrecked your defences, so he had the swing with Rd4. Instead, 40 h5 still looked fairly comfortable and white still has a clean threat on the queenside. You cannot hope the doubled pawn is much use anyway.

Rook endings are often difficult and frustrating. Being a pawn up is often insufficient to win in many endings, not just R+P endings. Sounds like you need to start learning some endgame FAQs

Check out my endgame blogs for fast fast relief

http://www.chess.com/blog/NimzoRoy/endgame-faqs?_domain=old_blog_host&_parent=old_frontend_blog_view

Maybe he meant two rooks against two rooks. This is very drawish and hard to win. Here is why.

• King plays important role in endgame as attacker
• against two rooks often the king can't attack effectively
• the defender on the other hand can often use his king as defender

I believe you had the chance to win a piece at move 34. Let's see. 

i second h5, i think on move 41 you should have sacked a pawn with h5 maybe you would have had even winning position