Go to the "Games" page, select a game you like and tap the Install button. You'll be redirected to the AppStore. Install the game and play it for at least 2-5 minutes. To receive more units be sure to play games from your Mixlist.
Remember to make sure that you open games through Mistplay, have your "power saver mode" turned off and are not playing any games for more than 2 hours per game per day.