Pretty simple.
Take a picture of your receipts after dining out.
Upload the picture to vona. If you're using a 3G/4G connection choose a smaller version of the picture, around 300-500KB.
Choose the items that are yours. You should get a total. From there you can add a tip to get to your total amount.
This is obviously only useful if you're with friends. So they can do the same. In the future we will allow you to share your receipts with them so they don't have to take the same pictures.