Cannot get a success message to display after form is sent (after validation).

Cannot get a success message to display after form is sent (after validation).

A website I'm designing – vgdesign.net/thc – has a form in the footer. It functions how I want right now (to my knowledge) except for the fact that after a user submits a form and it passes validation, I want a message to be displayed that says "Thank You". I have a class created for this in my stylesheet but I don't know how to trigger it when the form is sent successfully.

Essentially, I would like the result to look like this:


If the form doesn't pass validation, I want it to not display until the users fix the errors in the validation pop ups and resubmit.

The php script that sends the form contents to the specified email is at the top of my index.php page.
The validation tool I'm using is called jquery inline form validations (found here: http://www.position-absolute.com/articles/jquery-form-validator-because-form-validation-is-a-mess/)

How can I have that success message pop up when the form was successfully submitted?

Thank you!