Alberto Navarro on "[Plugin: Contact Form 7] Show differents HTML when select a dropdown"

Hello everybody, I have a special question.

I need to show diferent HTML when I make a selection in a dropdown (if is possible, without use the send button), exactly it's some different iframes.

I think that I need to use the Aditional Settings field, but I don't know how.

Thanks!

http://wordpress.org/plugins/contact-form-7/