Add control to custom contact form

[gius3pp3]

Hello,

 

I follow instruction of this topic to add custom form in cms page:

http://www.prestashop.com/forums/topic/285476-create-custom-contact-form-on-cms-page/

It work's fine

I'd like to add control for empty fields.

How can I do?

 

This is the page where is the form:

http://www.cantinevinci.altervista.org/contatti

I'm using PS 1.6

 

Thank You