How do I add a response email once someone has submitted their registration?

Do you mean to send an email to the form filling person after they submit the form? If so, you may setup an auto responder to your JotForm by following the guide below: 

http://www.jotform.com/help/26-Creating-a-Form-Autoresponder

If you want to receive the submission to your email, you'll need to add a notifier to your JotForm. 

http://www.jotform.com/help/25-Setting-Up-Email-Notifications 

Hope this information helps!