How do seve coffee in the cafe?

To serve coffee, first enter the lounge by tapping the Green Armchair Icon. Then enter the cafe by tapping the Coffee Pot Icon at the bottom center. Next, tap the Cup with a "+" Icon on the bottom right, which brings up your drink choices. Tap on the Coffee Cup and it'll show you how much it'll cost. Tap on the Blue Button to serve the drink. First one of the day is free. After that, it'll cost 10 diamonds more for each subsequent cup. 5 cups a day max. New free cup will be available after 23 hours.