World Series of Backgammon is partnered with the world's largest online gaming company bwin for backgammon.
Simply:
1) Go to www.bwin.com/wsob
2) Start up a player account (and create your own avatar! check it out it's very cool!)
3) Make a Deposit in with any one of numerous methods
4) No need for download - quick and easy 'in browser start'
5) Check the tournament schedules for tourney action
6) Check the lobby for money games action from micro to high stakes
7) Play carefully, don't steam! If you are losing more than you think you should, hit the books, watch WSOB TV shows to get yourself back in the swing of things!
Good luck!