Yep. A domain name is hosted using nameservers and these dictate which physical server handle things such as mail. The www bit is a record here and can either be a machine, or an alias to another address. For example, you could point the address www.mydomain.com to your actual webspace address www.myisp.com/myusername. Alternatively, sign up a proper web hosting account and get your site, and domain, professionally hosted. If you need more help in this area I'm more than able to give it, but I think plugging my professional services as a web technology consultant is against the T&C's of this site.