Please try submitting it to the "Featured" folder. If accepted the Founders will vote on it and add it to the appropriate spots. Thank you for you submission.
I'm sorry about that, it was the new "Hearts Boxcars" that you were trying to submit right? Very sorry about that, I think we have it fixed now but if it happens again let us know.
Well we don't really have any parameters set for that, and even then I'm not too sure of the pixel limit. I would say, mayhaps, about as big as the average stamp one would make for this site.