OK, so you have a premium Yahoo account, right? Therefore, you have some features that are not available with free Yahoo accounts. But, obviously, you would not give your username and password to other people. You don't want them to be able to change your "website", do you?
Have you ever actually registered a domain name with a
domain name registrar, so that you could have, for example,
www.amy.com, not something you create under someone else's URL such as att.my.yahoo.com/ ?