- Go to the Orders menu item and select the desired order by clicking on the edit icon
- Perform whatever steps you need to in order to complete the order - e.g.; find the item they ordered, put it in a box with an address on it, arrange for shipping, etc.
- When you have completed order processing, click the 'this order is complete' checkbox in the top-right corner of the screen
- Click the 'Update Order' button at the bottom of the page to save the change
Note: You can go back and update completed orders even though they look greyed out. Just click on the edit icon for the order.