How can I get my jotform form to link to Paypal?

When someone purchases something on my website through paypal I want my form to be able to be automatically sent to them.

How can I make that happen?

You can set your form as your Paypal Redirect: 

https://www.paypal.com/us/cgi-bin/webscr?cmd=p/mer/express_return_summary-outside

Otherwise, why not integrate your form directly with Paypal? You can do that within Jotform. Here are some guides that would help you integrate:

https://www.jotform.com/help/50-PayPal-Forms 

https://www.jotform.com/help/165-Setting-Up-Your-First-Order-Form