You have to learn somewhere, Liber, and trying to copy someone else's is a valid start. At least he didn't just copy and paste the image -- the window is on the wrong side of the door. (As for my opinion of pixel art as an actual artform, I'll keep that to myself for now).
I stumbled upon this the other day, Sgt. Beaver, it might help you out a bit more than the other site:
The Complete Guide to Isometric Pixel Art.