1. Come up with a secret for your characters! 2. Find an image off google or wherever! 3. Add your secret to the image. Online programs like pixlr can help here! Try to resize to about 400 x 600. If you'd rather not edit an image, leave a comment with text. 4. Upload your image somewhere like tinypic or imgur! 5. Share it here! Anonymous comments will be on until sometime tomorrow! 6. Guess other character's secrets!
And again, all secrets are strictly OOC knowledge :)