All the guidance for how to set the web up and process all requisitions and orders is all very segregated all the guidance notes need to be together from a person raising a requistion to the order being sent out. The videos should include sound with verbal instructions
You can find details of the workflow for both purchase requisitions and orders in the help:
Purchase requisitions
Introduction to purchase orders
The workflow for purchase requisitions and orders is segregated, as each workflow is intended for people working in separate roles - rather than being a single end-to-end process for a single person. For example, one person might have access to raise a requisition, a different person may need to authorise the requisition, and a third person may be responsible for processing the purchase order for that requisition.
This is reflected by the licences required for the different user roles. Purchase requisitions can be raised, authorised, and converted to orders by people who only have access to the Self Service web portal ("web user" access). People who have full access to the desktop app can further process the purchase orders, such as confirming receipt of goods and recording invoices.
Hope that helps.