Why does this happen to me on occasion?

I admit that I am not an expert player, my live chess rating is about 1200+ and my long correspondence chess rating is around 1600+, I know what some of my weaknesses are and the openings are one of them, I don't fully have a clear understanding of all the various opening book moves or some of the basic lines of interest that make any particular opening completely understandable. But on occasion i run into this position and usually get caught with my pants down. If anyone out their has some advice i would be very grateful for any insight to this game, by the way it was one that i managed to pull off with some creative play, others may disagree but it was interesting anyway. Here's the game.