Step 1: Finding A Box
Boxes are located in the last tab of the Design menu along with expansions. They cost 24 gems to open, and new boxes are temporarily placed at the front of the menu. You can scroll through the tab to find which box you want to open. Some boxes are no longer available and have been marked as 'removed' in Post 1 in the List of Boxes.
Step 2: Opening a Box
Opening a box, by selecting the crate, will award you with a prize which you can use to decorate your restaurant. Box prizes fall into four different rankings: Common (4th Place); Uncommon (3rd Place); Rare (2nd Place); and Exceptional (1st Place). The higher the ranking, the rarer (and usually bigger) the prize!
Step 3: Receiving a Prize
Box prizes will automatically be placed in your inventory, under the category in which they fall. Most box prizes are floor decorations, but you may also win a wall decoration or appliance depending on which box you open.
Step 4: Displaying Your Prize
Once in your inventory, these items can be placed in your restaurant just like any other market decoration. Voila!