I am selling computer parts and have a customer asking if I will
accept a PO. I know what a purchase order is and trust this customer,
but need to know what forms I will need to provide and what steps I
will need to take in order to 'accept purchase orders'.  Please
provide an example of any forms needed or let me know exactly where to
find them.

You don't need any forms.  You only need to have billing software
-available in any accounting software package.  A purchase order is a
standard form used by many businesses to guarantee payment to a
vendor. It is sent as a promise of payment and is used in lieu of
cash, credit cards, or checks.  Payment is made after the delivery of
the product.  For small businesses, this can be a difficult financial
cost to absorb.

If you can absorb the cost of the product and shipping for a month or
two, maybe longer, then all you need to do is say YES, ship the
product, then bill the customer.