Well, what I want to do is to do the following, first, how can I send information to PayPal through my PHP value of the purchase.
That is, the buyer selects the number of items and then click Buy, how can I get the paypal to receive the purchase value. In other words, if the buyer on the site selected items in the amount of 25 €, how can I do to pass this amount to PayPal, the 25 € and send a payment reference to later identify the user who paid.