Trying to not go to a different page after form submit...

Hello,
I have a form you can see at www.trilumina-temp.com and then click on the "Download Now!" link under the slider where it says "Download a Product Sheet" ..its not really a download though. I would like to not go to a different page after you submit the form, and just to show text or show a hidden div in the modal after the form is submitted saying "Thank you" or something like that. Is there a way I can do this? Thanks