Login to your SO account.
On the left menu click on Sent Orders.
Select one or multiple orders that you would like to import to your accounting system by ticking off the checkboxes (make sure you have an invoice number for the order).
You can filter your selection to only show delivered or completed orders.
Click the Export icon on the top right hand side.
6. You will have the choice to export to a CSV or XLS file. Make your selection and save your file.
7. Login to your accounting system and import the file.