To add a Customer and/or a Customer PO# follow these steps:
Go to the left menu > Categories > Select a Category > Quotes Tab > Create Order from a Quote
Once your Order is in the Draft or Pending states, there will be the "Edit" button next to the Ref#, and if you click it you will now see the fields labeled:
PO# - You can assign your own unique PO# separate from the auto-generated Ref#.
Customer - Type in your Customer's company name here
Customer PO# - Enter in the PO# you received from your Customer here
Then click the "Save" button at the bottom right of the pop-up
You can change the data here at any time in a Pending or Draft Order. If you update anything after the Order has been confirmed, the Order will go back into the Pending state.