You need to win all 7 Drift Attack events in the Shatter Bay Career. In Drift Attack you start with a timer and you have to reach a set score for each star. You get seconds added to your timer for performing longer drifts. These events can be quite frustrating at first but once you get used to of the games handling, you will earn the 3 stars with no problem.
The main thing to remember is you always need to be drifting throughout the track in any drift event, even on straight lines as the points all add up. The Shindo Wolfram is the best car for drifting as it is also the easiest to handle but you can experiment to find the car that best suits you.