There are no deadlines, and you can submit to any challenge as many times as you want.
All entries must comply with the letter and the spirit of the challenge and must have been painted after the challenge's posting date.
When you click the Submit to the Challenge! button on the challenge page, simply fill out the dialog form that appears. After a quick spam screening,
your submission will be posted on this page and available for other artists and potential buyers to see.
Best of all, you don't have to sign up for anything and there are no fees or commissions.