NTL provides only HTML support for web pages. (and javascript, but that's a browser thing)
One option, pay for some hosting, see Matt D's post, or if you don't have a need for paid hosting you can use a free 3rd party form processor.
I've used the service at
http://www.response-o-matic.com/ in the past, you basically point your form to their script. Info on the site.
Cheers
MikeyB