This part will require some manual entry if you do not already have PO data in a similar format. The important thing is that the SKU matches the SKU in the imported Amazon data.
An easy way to get a list of SKU and Title, the monthly Sum (Summary) sheets contain product lists for that month. It can simply be copied into the PO sheet, and the cost price and quantity can be added.
If you are having trouble with COGS data populating see this entry.