First change, the webpage title.
Log into the administration backend (
http://clan-nbk.net/CMS3/administrator/)
Go to the Site menu and select Global Configuration.
Four options down is the entry "Site Name" with a text box beside it, which'll have Mambo in it. Replace with your title of choice.
As for the copyright, that text is part of the template you're using. Its a default Mambo template, and it may be that the template is copyrighted itself (not certain), in which case you shouldn't remove the message. There are plenty of decent free templates out there which you could use instead. I use a customised one on my guild's site:
www.darkaffinity.com; took a pair of us about a week on and off to put together, critiquing the changes we'd each made to it.
