How to create, approve PO's - assign work items to me?

I’m new to AX and I would like to know more about the functional part of it. I want to know how to create and approve purchase orders. What are the steps to create and successfully approve a simple purchase order? The other thing is, I to assign work items to myself and access those in “COM/Home/Common/Work items/Work items assigned to me”

Any help is appreciated.

That’s the answer for my first question, what about the work items assigned to me?