If your yearnin’ for some learnin’ the GP team has On Demand Learning: Requisition/Purchase Order Workflow Setup and Overview for Microsoft Dynamics GP 2015
On Demand Learning: Requisition/Purchase Order Workflow Setup and Overview for Microsoft Dynamics GP 2015 – Microsoft Dynamics GP Community
Sales, Purchasing & InventoryInstall, Upgrade & AdminMicrosoft & the GP EcosystemGP 2015
Archived post from 2016. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.