IIS

Hi,
I am playing with Internet Information Services on my home network. I have installed and configured an IIS on my windows 2000 server. I created a default website as well. When I type in the IP address of my server computer, I gain access to myweb site. I want to give domain name to my web site. How do I do it? Do I have to buy a domain name or I can use my computer name to access my web site with out typing the IP address of my computer. I also tried adding header name to my website, butI guess it didn’t work. I don’t know what I am doing wrong here. Can somebody please help me? Thanks for your help in advance.