How can I link a payment question to a paypal account?

I have inspected your form and currently you are using Purchase Order Tool. If you want to connect your payment question to your PayPal account then you need to use PayPal payment tool. 

Inside of this guide you can find how to do it:

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

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

https://www.jotform.com/help/183-Difference-Between-PayPal-PayPal-Pro 

Hope this will help. Let us know if you need further assistance.