Heads up! This blog post hasn't been updated in over 2 years. CodePen is an ever changing place, so if this post references features, you're probably better off checking the docs. Get in touch with support if you have further questions.
One notable difference this year: you'll be submitting the designs through CodePen!
There are quite a few images in the design, so you'll need to host those somewhere. To make that easy, we've enabled a promotion in which you can get a free CodePen PRO account for the duration of the contest. When you are PRO, uploading files is as simple as drag and drop onto the preview area in the editor.
Just to be clear, you don't have to work in CodePen if you don't want to. But you do need to submit the final design through CodePen.