Win Surfin’ is an event that you'll find in the Event Center when it is available. Your goal during the event is to win a streak of new levels, up to a max streak of 4. Each win will provide you with access to better Starter Cards while playing the event. One win gets you an Extra Stock, two wins gets you a Split Card, and three wins gets you a Wild. Any wins beyond 3 will earn a MAX STREAK, giving you access to all 3 Starter Cards while you maintain the win streak.
You'll find all of the Starter Cards immediately when you start a game, and you can see your current streak before you start a game, to the left of the "Play" button.