There are two steps to this, maybe less. The name that goes into the URL is resolved by the DNS (sorry, but you must know DNS and URL and I will not explain what a DNS is.)
First, you need to register (pay money!) to get your reserved domain names out on the internet naming service (DNS). Now that both names point to your server, then read http://www.unix-girl.com/geeknotes/apache_virtual_host_conf.html to see how you may have virtual hosts on one server.
I would like two domain names to be interchangeable. In other words, if the browser inserts one domain name in URL box it will refer to the same website as the other (and possibly change to the original domain name). How do I set this up?
And do you know of any web hosts that provide two different domain names for the price of one?
Thanks. I'm new to this.