The members site is hosted on Google sites, as is this one.  It is a private site and to log on you must use the email address the BDA has on record for you.  You were sent a link to the site to that email address.  If you want to be able to log on using another email identity let us know.
Here is a link to the site:
http://sites.google.com/site/bdadentalmembers/Home/
To log in you have to set up a Google account using your email address as your user ID.  You make up your own password and confirm details with Google before you can log in.  Let  Bill Hunt know if you have problems.