It seems I have finally reached 11k on KGS, but I feel like a 15k at the moment.
I just played this game and since it's April 1st the black stones where pink and the white stones where normal now there was no dark colour and that may have confused me a bit, it looked kinda funny

Anyway until move 116 I was far behind and even after 116 black was still winning.
Black looked so strong, so where did I messed up to allow black to become so big and strong?
As you can see my opponent and I both used a lot of time for most of the moves.
The there is black invasion on the lower left corner where I messed up, well I won the corner back and managed to drag 2 dead groups to safety and won, but luck like that won't make me stronger^^

So any comments would help me from the beginning to the end. If you have some harsh things to say about some of my stupid moves feel free the say it harsh, I'm willing to learn from my mistakes

I don't have time for a full review, but the gist of it would be this: Think about what your moves are doing. Don't play moves that cut two live groups, don't waste time trying to save stones that are doing absolutely nothing, (like, they're not cutting stones), don't waste moves capturing single stones that are doing nothing, and in general think about what you're accomplishing with moves before you put them on the board. Every time you waste a move doing one of these things, it's like giving your opponent a handicap stone.

edit. oh you're white. nm, i'll post a review later

Look under the File menu.

I count about 5 worthless moves in the middlegame. If you could take those back, and put them in 5 useful places, how much stronger would you be?

Thanks EdLee that are some important points.

@Shaddy: Thank you for this great and well explained review!
I can see you took some time for this great review, so I'm going to learn as much as possible from it, now I can see where I need to keep working on.