Gathering from our tweet exchange, here's a more detailed explanation!
According to our servers, your friend doesn't have any one-click installs (such as Wordpress, Joomla, or Concrete5) associated with alcmusic11.com. However, home.alcmusic11.com does have Wordpress installed to it. So basically the answer you're looking for is that alcmusic.com is not CMS -- it is a custom built site. Administering the site via "administrator" or "wp-admin" only works for CMSes.
To make changes, you'll need to edit the html files for the actual site via FTP. THe home page is: index.html. You'll need to login with FTP with the user alcmusic. I'd suggest confirming with your friend that it is in fact a hand-built site (not CMS), and get the FTP login from them. If that's the case, this article might be helpful: http://wiki.dreamhost.com/Ftp
If you have questions or need help with any of this, please don't hesitate to contact our support team here: https://panel.dreamhost.com/index.cgi?tree=support.msg& or here: http://dreamhost.com/contact/ (if you don't have access to their DH panel).
Hope this helps,
PS. I'm a dude-ette