Edit: Problem solved! I think it's just my internet connection...
So I actually, miraculously, drew something that I think is halfways decent, and deviantART is all like, "NOPE! Won't let you upload sucker!"
I try to upload the file, and it uploads to 100%, but then it's just stuck there processing forever. I tried leaving it for about 15 minutes, nothing. So I refreshed the page and tried again - nothing. Lather, rinse, repeat. Still nothing.
I DON'T KNOW WHAT I'M DOING WRONG