This dynamic functionality is not supported in Publisher. You should look to
a server side solution for a database. Perhaps ASP, PHP etc.

Alternatively if you do not have many customers, you could create subfolders
on your site, and create their information with separate Publisher files.
You could also make those subfolders password protected if you wanted. Look
to your webhost for how to create password protected folders. It varies by
the host.

DavidF