how do i make a message for closed form

I'm not sure if I understand your query correctly. Do you mean to say that you want to display a message to the form filling person if the form registration is closed? If so, you may set an expiry date to your JotForm or limit the form to receive a number of submissions and display a message from the Form Preferences. 

Please see the screenshot below :

Please refer to the guide below that can help you with limiting the form submissions.

http://www.jotform.com/help/137-How-to-Limit-Submissions-in-a-Form

Hope this information helps. Let us know if you are referring to something different or need any further assistance. We will be happy to help.