Guess what episode the picture is from.
If you don't know, you can ask for a clue. You can be specific [ie: What season is it from?] or you can just ask for a general clue. Clues are unlimited, you can keep asking until someone guesses right.
Whoever guesses the right episode posts the next picture.
Everyone who participates must check the forum daily. If someone takes longer than 4 days to respond [For example, if the winner hasn't posted a new picture or responded to tell someone whether they guessed correctly or not] a new picture can be posted by anyone.
Have fun! :)