You can check here the latest results of the finished competitions. Everyone participates automatically but you need to claim your prize within a week after a competition ended. I added also extra points with your prize so you can claim faster this amount to your micropayeer! You can see from June 2018 also the id-number of the bitcoinadress.
Latest competition ended 15th August = claiming before 22th August = old prizes! The two-weekly competition has the higher prizes!