Please help me understand my Errors

Hello. I have just played a game which I won, but after making the computer analysing the game I found out there were many errors (4) and 1 serious blunder.

I really didn't understand the errors, not even the blunder actually. Would you please help me why the computer counts the lines I'll type later as errors and blunders?

My thoughts on the blunder:

Perhaps it's a blunder because I traded my good Bishop for the bad positioned Knight? Mh..

For example g5 is very bad because exf Bxf6 Nxg5 Bxg5 Qh5 and black has lost more than a pawn, he's busted.

Oh, now I see why that one's bad. I didn't see that! But since it's marked as an Error, was there an option available to Black to save the game? If white moved the way you said.

Oh wait, nevermind. I could've eaten that pawn with my pawn, is that it?

I don't know, you should probably try to work it out for yourself.

Thanks IMBacon!

Dont thank me yet...Im probably wrong on some if not a lot of this.  This is just what i see.  But at least if give you something to think about, and hopefully someone better will come along, and give you some real advice.  And hopefully we can both learn something :-)

Almost all of your mistakes are because you're missing that exf6 is quite strong for white, and you need to make moves which take away that threat. 

Someone should tell karpov