I blew a winning position in the End Game! Help!

Maybe you can move your king up and then sacrifice your queen so you can eat rook, but pay attention. King must be in f4 and your queen must end at e5, so you can beat his pawn, then his other pawn... Or i guess, maybe you should try.

44...Ke7? loses, but black had the stunning 44...g5 45 Qxg5 Kf8 to reach a drawing fortress.
47 Qc7+? indeed allows a drawing fortress.
You had to disrupt his coordination with 47 Qa3+ Kd7 48 Qf8, winning. Also 47 Qc8 as you said.

Any good endgame book has more examples and explanations.
Classical examples:
https://www.chessgames.com/perl/chessgame?gid=1036749 
https://www.chessgames.com/perl/chessgame?gid=1240242 

If your king was on the d,c,a,or b files you would win because you could sacrifice your queen for the rook and pawn, resulting in a winning king and pawn ending.

On move 39, with black to play, the position is a draw.

to understand this structure you must break it down to its simplest form.

As you can see black can achieve a fortress quite easily when there are few pawns on the board, White's goal is to push black's king away from the f7-pawn (by keeping the king away from g8 & f8).

Black didnt have to allow 47.Qc8+- but created a fortress we already know with 44...g5!

Look at it this way... You learned something about a fortress! So, with that in mind, next time you won't be in a hurry to simplify the game the way you did. Perhaps another plan will be required.

This is a good, instructive game that you can learn a lot from. And at our rating level, learning, not winning, is what matters most. Cheers!

You messed up by trading too many pawns and getting all the pawns on the same side. When he sacced his bishop it was a draw, but he blundered with g6. You could have won by bringing your king in to h6

Instead of playing g6,your opponent could have drawn with h6,followed by g5. If your opponent did that it would have been a drawn rook and pawn vs queen endgame

Queen vs rook with equal pawns is usually a win,unless the position is a very simplified blockade. the way to win is to keep pawns on both sides.also look for opportunities to sacrifice your queen.for example,the position below is a draw. If you sac the queen it is a drawn pawn endgame.

Now put pawns on both sides and the black wins easily,as he can sacrifice the queen for the rook and pawn and win the pawn endgame.

is this not in Dvoretsky's Endgame Manual page 237?

its almost exactly the same

On move 39 your opponent's best try was h6. Here is how to win if he had played it.