If you've entered before you know how it works
If you would like to enter then you need to be IN from round 1, else you won't be entered into the league. The Prediction league has been running for many years, over on Competitions - between myself and Sputnik - you simply guess home win, draw or away win for each Championship fixture (+ a guest game), as well as trying to guess the correct RFC score.
You can read the rules here
viewtopic.php?f=9&t=127762
Round 1 is here
viewtopic.php?f=9&t=133163