The servers for this game closed on April 15, 2012. Unfortunately, this means you can no longer earn this achievement.
Select Race Day from the main menu and choose an event that has activity (which is indicated by the colored bar on the left of each event). The bottom right location seems to be the most popular.
Select the location and then choose Multiplayer.
If the location is in the middle of an event, you may need to wait a while until the next event is ready. You need to complete one event to earn the achievement. You do not need to win.