newbie question for apache config

Ok, I have gotten bits and pieces of info reading some posts and have learned a lot but still
need some help.
I have just installed apache 2 and have configured it to:

Listen 8004 since my ISP blocks 80 and 8080(I have an Abyss server running on 8003 so I know that is not the problem)

my documentroot "C:/Program Files/Apache Group/apache2/htdocs" and directory
"C:/Program Files/Apache Group/apache2/htdocs"

my server name I have set to my ip address and port even though I have a domain name since i eventually hope to use my virtual host cofig

my router and firewall are allowing the port and i can access local host

why cant it be accessed by www.example.com ?

I use DynDNS.org for my redirection and with the upgraded service I can specify a port unlike other services. I have windows XP home edition if that matters. If anyone can help or direct me to an example config file that I can model mine after I would appreciate it very much. Any Apache config tutorials would be great. Thanks in advance.