How to enable/disable Submit button

[Webmaster]

I would like to know how to enable and disable the submit button.
It will be enable only if the user is on an specific web page.

[Admin]

You need to Add Dynamic XML from your server like ( http://www.mysite.com/include_xml.php?url=%url) - the script will check the current Url and if it is the page needed, returns Include XML with a Submit button, otherwise without this button.