From the main menu, select WNBA. Select "The W" and create your own WNBA MyPlayer. Once this is done, go to the "game day" option and play your first career WNBA game. If you win, this achievement will pop but if not, just keep playing games until you do grab a win. This achievement can only be obtained after creating a WNBA MyPlayer and winning a game in your career. I played several WNBA quick play games and achievement didn't pop for me despite winning all of them. It seems you must win in "The W" game mode for the cheevo. Hope this helps!