The DNS problem For people to find your web server you need an entry in one of the DN servers. You can use a free service like no-ip.com or dyndns.com. Open a free account, setup is a breeze.

Or buy a domain name through a registrar for like $9.99/year.
If you going to use Yahoo, they are NOT registrar, plus they attach a banner at the end of your pages. To avoid that, open a free account on freedns.afraid.org and in the Yahoo admin page change the name servers to point to afraid.org, which points to your IP.
If your IP is dynamic follow the instructions on their website and download an IP updater.