The 'Decoration' feature unlocks prior to Level 7-1, where the tutorial will guide you on how to purchase your first decoration. After 7-1, the 'Decorate' button (a hammer and paint brush) can be accessed prior to each Level, or by clicking on a restaurant on the map. Decorations are super cool! They look great, of course, and allow you to personalize your restaurant. But they also increase your chances of receiving FREE Whisks and Coins each time you complete a customer's order! Each restaurant in the game has its own decorations, so be sure to check them out each time you unlock a new restaurant.