in laymans terms, whether or not i can create a web domain on a redhat linux machine. ie if i want to run www.blahblahcrap.my.com or .org or whatever do i need to pay to have that site? and will other computers be able to access my web site from their internet explorers?

You need to register the domainname and point it your ip (hopefully not dynamic). Finally you need some httpd running to serve pages...

If you use a dynamic ip, then your best bet is some of the free dynamic dns services (ex. http://www.dyndns.org) - you can get a dynamic dns entry like myhost.dyndns.org for free there.