I am uncertain if you already have a server on your machine, however you will want to download one (a server). The best around is obviously Apache
. Once downloaded, install it to C:\Apache (Not the default C:\Program Files\Apache Foundation folder). Afterward set up your Internet Modem to forward port 80 on TCP and UDP to your computer's IP address (Not necessary if you're not behind NAT or a firewall)
Once you've done that you have a running web-server. Any document's you place in Apache's, "htdocs" folder will be accessible from the web.
Now to get you a DNS. Try out DynDNS
. They have free services (which I myself use) and some services which cost money. Most likely you're after a domain name, so you're going to end up paying for your DNS services. However once you have an account you will want to forward any traffic dialing the DNS to your computer's IP Address
After the DNS is setup any traffic visiting your DNS will be forwarded to your computer's IP address where Apache will direct them to the files located in its, "htdocs" folder.
Let me know if you need me to clarify any one of the previous points, I will gladly do so.