What courses to study to solve the problem?

I have following problem: I want to have on my forum one HTML page with technical drawings. The drawings will be available for download, but before download the user should contribute certain amount of money via PayPal.
What courses should I study to be able to fulfill this task?

Thank you a lot for the advice! :slight_smile:

Kind regards.

You might wanna take a look at this:

PayPal Payments Standard integration guide
PayPal Express Checkout Integration


It’s helpful i think is.