yeah, i made it 800x600, but i guess tinypic doesn't host anything that big. I think they resized it.
Thats pretty good for a starter, I've never done walls myself but I know there hard to do. Try adding some pic effects to it and a little brushing in the bg.
Tiny pic does support 1024x768 walls. I always upload mine on there. But now i got DA so i don't anymore.