You start by making an exchange. It has to be 10 diamonds or more:
Then it will scroll you down to the Wheel. You hit "Go" if it's your first time playing or "Play again" and then "Go", if you have played before.
The Wheel starts spinning and you get a bonus:
You hit "Go" again. Now I got a re-play bonus, so I get all empty cells respawned. I still keep my previous bonus, though:
You hit "Go" again and get another bonus that summs to the one that you had before:
And so on you keep playing, until the spin stops on an empty cell. When it does you get the option to apply your bonus or to play again:
If you choose to play again, the bonus that you have selected before will be reset and you'll start the game from 0 again.