1. Go to Commerce and select Invoices.
2. Choose the option and click Create Invoice.
3. Enter the Billing Contact and Company, then select the Billing and Shipping Address. (Optionally, add a PO Number.)
4. Click Create Custom Line Item.
5. Fill in the required details.
6. The line item will be added to the invoice.
7. Click Create.
8. Your invoice is now successfully created.