can i add my own code for payment into jotform?

Hi,

If you are trying to add a coupon code to your payment form, you can do so by following this guide:

http://www.jotform.com/help/233-How-To-Add-Coupon-Code-in-the-Payment-Form

Please let us know if this is not what you were looking for and we will be happy to assist you further.

Thank you for using JotForm!