When a Supplier Invoice has been saved it is stored on the Supplier the Supplier Invoice page, where it can be found and opened.
...
The Supplier Invoices page displays.
The Supplier Invoices page provides comprehensive search functionality, including search by Invoice Number, Supplier and Status.
To open the invoice click it's Number link (e.g. 234 in the example above).
For information on how to process a Customer invoice see Supplier invoices Service Provider.