If you have the members personal information stored in the database,
like their username, password and other information, then when a member logs in,
the script needs to query the database for this member and verify that they are whom they claim to be.
If everything checks out good then display ther username on the page.
This way you can use one web page for all members.
If you keep passing their username from page to page,
then you can make it appear like this is their personal website.