How do I attach my PayPal account to my form?

In the Form Builder, open the "Add Form Element" window and select the Payments tab. After that, use the search bar to locate the PayPal Payment Gateway. 

I am not sure what PayPal you're going to use but if it is PayPal Standard, please follow this guide: https://www.jotform.com/help/391-How-to-Integrate-Form-with-Paypal-Standard-

Let us know if you need further help. Thank you.