ID unique that is sent to the user filling out the form

how to return the form to the user that it has fully filled with the id unique serial number generated after sending?

You can add a Unique ID widget to the form to give each user a unique ID for their submission:

http://widgets.jotform.com/widget/autoincrement

Create an autoresponder email to send a response email to the user filling out the form:

https://www.jotform.com/help/26-Setting-Up-an-Autoresponder-Email