Domain names are just fancy ways of getting a plain numeric IP. When your computer looks for google.com, it's looking for a DNS server, looking to see what IP address is associated with google.com, and then it accesses that IP address. The browser will tell you it's google.com, but it's actually, for example, 72.14.207.99 (this is what my DNS search found).
http://www.google.com is the same as
http://72.14.207.99 but "google.com" is easier to say and remember.
You basically go to godaddy.com or some other place that sells them, give them however much for some domain name, and they'll spread the data associating your IP address with that particular domain name you bought, so anytime someone access Titaniumsdomain.com or whatever, it directs to your computer. If you don't have a server of some form there, it's pretty much useless.
You can do this to single IPs, I'm not sure about doing it to a whole network.
Edit: Unless you mean subdomains. I've never worked with subdomains but I don't imagine it's hard once you've gotten the domain name. A subdomain wouldn't be
[email protected] or whatever, that'd be an email address probably, it'd look more like alloy.titanium.com.