I just registered, paid my $25 fee, but I can't find any way to add any prints to DCPrint. I read the help FAQs, they tell you how, but I can't find any links that they mention.
Then it gives an option for a printable file. That's where you put the file of suitable size and shape for dpcprints, which then has to be approved for sale.
Sorry to be so concise and abrupt - it's way past my bedtime.