Clicking the external link will take you direct to a lil downloadable gift, a sticker for your contest book (should you choose to create such a thing, of course!) courtesy of MadMikeMarsbergen & LayethTheSmackDown!

It is, apparently, quite simple to attach said sticker to your cover.

Simply open up the sticker file in Paint or Photoshop, and then you copy-paste it onto the image of your cover, which you would open up in a separate instance of Paint (or the same instance of Photoshop).