Could anyone suggest how I could've done better in this game?

At first glance 15. Bg3 seems the more natural move.

I moved by rook instead to both generate a threat on my main concern, the bishop and to preserve the possibility of creating a fork between the king and the queen, which I in fact did later in the game.

Although, that might also be a good idea, thank you for the response Dan!

No worries John, far better players than me will soon give their opinions on your game, you will take something away from this I am sure. Although in future I recommend posting up losses rather than wins as you will learn even more. Good luck out there....

After black played 6. ... Nf4 you had the opportunity to win a piece. Why not just take it with 7. Nxf4? If bishop takes, queen takes.  You played 7. Kf1. This was not a great move for two reasons. Firstly, you missed that you could have won a piece and that would have made the game a lot easier a lot more quickly. Secondly, Kf1 is not such a great move anyway. It means that your rook on h1 is not trapped and cannot easily get out. If you were going to move the king you should have played O-O to bring the rook into play.  Maybe your mouse slipped and you meant O-O rather than Kf1?

Not only did you miss the opportunity to win a piece with Nxf4 but you didn't notice that black could take your knight on e5. So with this one move (Kf1 instead of Nxf4) you went from being a piece up to a piece down. I don't want to be harsh but if you miss this sort of move (that is, if you don't notice when you can take material or when you can win it) then all of the other stuff about strategy and open lines and centre control becomes irrelevant. 

However, you played well after that error and well done for spotting Bg5+ winning the queen. 

7. Nxg4 wins a piece because you attack it twice and your opponent defends once

15.Bg3 or 15.Bg5 moving your attacked and undefended bishop while attacking his queen. This makes him lose time allowing you to play 16.exd6

16.Qg1 to defend your h2 pawn

18.exd6 take with the pawn because it is less valuable than the knight. A knight or bishop is worth about 3 pawns. Your opponent should have responded to 18.Nxd6 with cxd6.

21.Rxg7 notice how your bishop has no moves? Your opponent is threatening to trap it. More importantly however, notice that your bishop is on the same diagonal as his king? That means his pawn on f6 can't move. Also notice how your queen is on the same file as his king. This means that if that file ever opens you will be attacking his king. So if 21.Rxg7 dxe5 22.dxe5 is check.

No further comments. The exercise I recommend is to go through this game yourself and list every piece that is undefended and attacked or attacked by a less valuable piece, by you or your opponent on each move. Start doing that on every move in each of your games. When you get good at this you will probably improve your rating to 1000.

If you are serious about improving, when you are done with the list go ahead and post it here. I will help you by telling you on which moves you are still missing undefended pieces.

@corum Yeah, the Kf1 was a mouse slip on my part, that was the blunder I mentioned on the post, mistyped f1 as f8, sorry. I planned to castle and THEN attack the knight, but I sorta went into panic after I slipped and forgot about it. Thank you very much for your reply, it is sincerely appreciated. 

@TS_theWoodiest Your detailed suggestions are much valued, thank you so much for responding with such well explained improvements, as for your self-analysis strategy, I will surely take that on board and do so for my future matches. 

@JohnMackey101 If you are pasting games variations go inside () and straight chat inside {}

1. e4 e5 ( ... c5 ) {black is chosing king pawn over sicilian}

Correct. I meant 7. Nxg4 after 6...Ng4?? was played.