Linksys Router - Apache Server

Hi,
I have recently installed the Apache server software on my computer. I
have a Linksys router in which I use to connect 3 computers to the
internet with. I have a DSL internet connection.

Here is the problem. I can connect to the server via the
http://locaclhost url in my browser locally. However, if I were to use
my free domain name that I signed up for it does not work.

I do not have a static IP address, it changes everytime I connect to
the internet. However, the use of apache is for knowledge. I am able
to find out my current IP address at the time and I redirect the free
domain name to that ip. (http://xx.xx.xx.xx)

That is where the problem lies. When I use the free domain url and
type it into my browser, instead of seeing my Web site, I get the login
screen to access my router settings. Is there anything that I must
change?

I also run Sygate Personal Firewall, but that doesn't seem to affect
anything.

Appreciate any help, thanks.