On the League Office page (where you see standings), just below the WhatIfSports header and SLB in the upper left, is a "Play LIVE" link. Click on that, and on the new page that opens up click on "PLAY LIVE". You can try it out by entering one of the OpenPlay links, and start a game against the computer by clicking "Click to JOIN!" Or go into SimLeague Venue 1, where you're likely to see a list of other people who are on and waiting to play some games, Use the Chat window to ask for help getting a game started.
Feel free to sitemail me if that's not clear.