After you have motioned start, you'll be taken to a screen that says (from left to right) Show off & Share, Adventures, Free Play, Play Online, and Timed play. Pick the orange one that says "Play Online". After you have picked this option you will see 4 of your friends pop up in little circles, and below them from left to right says, Invite, Gamercard, random player, and an arrow containing the word more. Choose the option that says random player, if you have no one online playing kinect. If you do then scroll through using the more arrow until you find your friend playing. Once you've found your friend or random player you will play a match with them, once you have finished the complete 3 rounds of the game the achievement shall be yours!
Note: The three rounds only pertains if you're playing rallyball, popping bubbles, or plugging holes, you will also get it if you finish your time doing the boat or track game.