help with pay pal ipm sending/recieving variables on donation button

for PayPal i开发者_如何学运维pn are the variables set or do I set them? On a donation button how do I find out the amount that was donated? How do i make a fake donation in sandBox?

Thank you in advance. If it is to complex for simple code snippets can we im sometime?

Paypal provides code samples for this.

There are tons of tutorials for this as well. A very detailed tutorial (with video) - http://net.tutsplus.com/tutorials/php/using-paypals-instant-payment-notification-with-php/

Donated amount is obtained from the IPN request itself.

You cannot test IPN in the sandbox directly. Paypal provides a form to make in IPN call from the developer tools. Just login to the developer's section to check it out.