Set up PayPal Payment Center page

Set the PayPal payment functions on this page [login to view URL] Customers need to be able to select one hosting option and/or one web site design option, click "Buy Now" and then the page goes to PayPal. At PayPal the item(s) and amounts selected need to be listed on the PayPal checkout. As administrator, I will need to be able to change these prices easily (either in the html code then FTP or with an admin login) without messing up the php function.