I am the greatest!!
It's fairly simple--One person draws while everyone else guesses what it is. You get 10 points for being 1st, 9 for 2nd, etc. (stops at 5), and you get 10 points if your drawing gets guesses, plus 1 point for each one after the 1st. 10 rounds in all.
Be sure you have the upper chatroom selected when guessing, or you are just chatting.