Start a new game. Preferably Turtle Mode.
Play the game naturally (or use the hints) but avoid the orange and green tiles
Keep playing until you see three pairs of orange and green. For example: Orange Pair, Orange Pair, Green Pair etc...
Click each of them in pair one by one until all three are done. Do not select any other normal pairs during this. Once you are done either continue playing if not unlocked or you will see it pop up! Hope this helps