Dreamweaver needs tho have a PHP page open so that it knows 2 things?
1) What Dynamic language you are using
2) What site it should be using.
normally, with a dynamic site, all pages would be php, so instead of having index.html, you would have index.php
then opening that page, you would start the Security Assist wizard.
Security Assist cannot add access restriction to a .html page, so it really does not make sense to redirect after login to an html page, that page would be accessible whether the user is logged din or not.
The standard practice would be:
Open index.php and start the security assist wizard.
after the security assist wizard is completed, it will open the access pages manager, select the php pages that should only allow access to logged in users and apply the logged into <your users table> access rule.
if you want to change the redirection for login success, open the login page, open the server behaviors panel, and double click the Security Assist Authenticate user server behavior to change the login success page.