1. When you need to add a comment?
In some special situations, to remember about your order, you can add comment to it so that you will easily check it later. The comments on order are used internally.
2. How to add comment?
Click on the Note icon in the top right corner and choose Add Order Note. Then a popup will appear so you can add comment into the box.
3. How to check comment?
* In Web POS screen
To view comment of order, you can go to Orders tab in Web POS screen, choose an order then scroll down to see Comment History.
* In Magento backend
Go to Sales > Orders > click on a specific order. In order details page, scroll down to Comment History tab to check whether it has any notes or not.