Looks like you need to implement the Express Checkout documentation located here.
In an Express Checkout flow, a buyer still checks out at thebeginning of the flow and pays on your site; however, the buyerdoes not reenter shipping, billing, or payment information, becauseit is already available from PayPal. This simplifies and expeditesthe checkout process. The buyer can then proceed to review the orderon your site. You can include other necessary checkout steps. Youcan also up-sell to the buyer on your Review Order page.
(Others have noted the teribble formatting of the paypal documentation in its current state, namely the lack of spaces. Hopefully they'll get that sorted out soon.)
You can use GetExpressCheckout
to get a customer's shipping information so that you can store it. As stated in the documentation GetExpressCheckout
"obtains information about the buyer fromPayPal, including shipping information."