To print a receipt for a given order step 1 is to bring up the orders full detail page. Then on the right hand side of the page you'll see a digital version of the receipt showing each ticket and any items detailed to the order. Towards the bottom of that section is a print receipt button. Press this button to trigger the printing of a receipt.

If you have a cloud print connected printer, the receipt will then come out of the printer. If not you'll see a new tab open up with an image of the receipt. You can then use the browser print (file -> print, or ctrl + p) to print things out of your default printer.

The specifics of what is included in a printed receipt such as customer address or preferences can be customized via setup -> settings -> print settings, but the below image is an example of what the receipt can look like. The customers information is displayed, item descriptions and add ons are shown associated with the item and any taxes and fees are listed. The receipt will show amount due for orders that have not yet been paid, or the amount paid for orders which have been paid already.