Sorry this is a very noob question, but how do you upload an avatar? I know it has to bee 100x70, .gif, and under 10kb. Other than that, how do I do it?

Ok, so yep I'm a newbie to Threadless, but I do have a few years practice with photoshop and other art websites like deviantart.

So I wanna jump right in! I have an idea in mind that I think would be good right off the bat, but I need a little help. What kind of dog looks cool to you? The design will have a dog's face on it (don't worry it is more in depth than that, I just don't want to give the whole thing away just yet) and I'm not sure what breed would look neat. The dog will be in black and white, just one color print, so think of that. I was thinking of maybe a jack russell terrier?

Also, just any tips and trick in general that you think would aid me would be awesome!