How do you create a credit note for a vendor

How do you create a credit note for a vendor

Hello,

How do you load credit notes given to you by a supplier. For example I have a situation where I have receive 2 invoices from a supplier and then been issued with a credit note to reduce the total amount owed. How do I load a credit note for an invoice or part of an invoice from a supplier. I have loaded the invoices from the vendor as bills and am trying to process the payments.

Dion