Hi, i don't want thank you page but just a message in the same page of the form. is it possible? ( sry for my english

Hi,

The form will always redirect to another page when the form is submitted.  You can customize the message or the page the form is redirected to:

http://www.jotform.com/help/211-Setting-Up-the-Thank-You-Page

However, it is not possible to display a message within the form itself. 

You can redirect them back to the form by changing the thank you page URL to the forms URL.  Though this will not display a message stating there was a successful submission.