1. You need to register your domain name frist. It costs about $15 a year.
2. You need to find two domain name servers to serve your domain name. The domain name regisstrar normally offer this service on an extra charge.
3. Regarding email, you can either run an email server on your own P4, or use the domain name registrar's add-on service (probably with some extra charge).
4. You need a static IP address for your P4's Internet connection. If you don't have a static IP, you have to use dynamic redirect service.
I'll be happy to help out if you need. Just send me an email at zwt66 @ yahoo . com. (delete the spaces in the email address).
Good luck!