Next to playing your own matches, you are also expected to referee matches from other teams. When you are refereeing you (of course) need to lead the match, but you also need to note down the score, and give the final score to the committee. The score form that needs to be filled in should be available on the table in the hall the game is played.
When you select your team you can see when you have to referee (and when you have to play).