This is a compile of a few links you will find on the blog is you are interested in learning some of the basics of setting up and using External catalogs aka Punch-Out catalogs in procurement.

Basic Experience

Here are a couple of posts on the experience of using an external catalog.

Purchase Requisition with External Catalog AKA Punch Out.

https://organicax.com/2014/08/06/purchase-requisition-with-external-catalog-aka-punch-out/

External Item Handling with Punch Out Catalog

https://organicax.com/2014/10/16/external-item-handling-with-punch-out-catalog/

Setup External Catalog

Here are a couple of posts on setting up an external catalog

External Catalog AKA Punch Out Setup

https://organicax.com/2014/08/06/external-catalog-aka-punch-out-setup/

Procurement External Catalog AKA Punch Out Concept and Setup

https://organicax.com/2015/04/12/procurement-external-catalog-aka-punch-out-concept-and-setup/

Punch Out Catalog Message Handler Protocol Setup

https://organicax.com/2015/04/15/punch-out-catalog-message-handler-protocol-setup/

Return URL Setup on Punch Out Catalog

https://organicax.com/2015/04/17/return-url-setup-on-punch-out-catalog/

Modifying a Message

This posts covers an example of things that you might need to consider if the message between the supplier site needs to be modified.

https://organicax.com/2015/04/17/handling-different-suppliers-shopping-basket-with-punch-out-catalogs/

Cheers

Lachlan