When you join the site, you will input your playing level. You will have the following options:
2.0 - beginner
3.0 - good
4.0 - intermediate
5.0 - advanced
6.0 - semi-pro
As you play ladder, league, tournament and practice matches, the site will create calculated singles and doubles playing levels.
The calculations are based on a mathamatical system called the Elo System
The system takes into account your opponent's calculated playing level, and the accuracy of each player's calculated level.
So, if you register as a 4.5 player, and you beat some opponents with higher playing levels then you, your calculated playing level could increase to something like 4.65.
The calculations are done each night, so there is small delay between when you submit your match, and when your calculated levels are updated.