To use PayPal, typically you write the seller a pm to get his email address, discuss anything else like postage, and give him your mailing address. If he no longer sells these or is unavailable you'll stop at not getting a response. It sounds like you got stopped here till he writes back. The PP address is typically the email address so my suggestion would be to write to him at it (again?).
If you are confused by the PP part, you simply go to PayPal and use his email address to send him the payment. There will be a comment box and you should also put your mailing address and contact info in it for him.