how do I change the e-mail address on a contact page

I am creating a simple contact page and I want it to go to my clients e-mail  address

I have inspected webpage you provided and I was not able to find JotForm form on that page. 

Do you want to change email address to which email Notifications are sent once your form is submitted? You can do that inside of Email Notification by changing Recipient Email address.

Inside of this guide you can find out how to set Email Notification:

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

In case that you want to send Email to Multiple Recipients please read this guide:

http://www.jotform.com/help/39-Send-Notifications-to-Multiple-Recipients 

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