The following steps will walk you through the creation of an invoice.
If the order is not attached to your account, go to the attach orders page to attach the order to your account.
See also: How to attach orders to your account
Once the order is attached to your account, click on the Your purchases button on your user profile. On the purchases page, click on the Invoice button next to the order you want to generate an invoice for.
You can edit the bill-to information displayed on the invoice by clicking on the Edit your profile button on your user profile, then clicking on the last tab, Invoicing.