Actually Mae, its kind of easy. All you have to do is start a fan site for a player that you become friends with, then spend the next two years of your life trying to figure out all this rankings stuff
Seriously, the easiest way to start is to look at Tommy's activity page at the ATP website and see how well he did last year. Start on his profile page:
http://www.atptennis.com/en/players/...yernumber=H355
click on 'his activity' on the right side, pick the year and click on Singles. Then you can see that he got to the Semi's of San Jose and Memphis, so he got points for that. Points are good for 52 weeks, so those points will come off in February and he will need to earn points to make up for it. So every Sunday night, the ATP subtracts some points, and adds more. Hope that helps a little bit, but I've kind of confused myself now.
{Hope no one else minds, Mae is a relatively new tennis fan and is learning all the technical stuff, so I try to help her whenever it comes up in conversation}.