If you have purchased the domain name the company you purchased from should be able to foward to your home IP
You might go check out http://www.dslwebserver.com/ for more information on configuring your system. Turning off your ping response will also help make your system harder to find by hackers.
Do you have a fixed or static IP address? Home IP addresses are typically dynamic unless you upgrade to a static IP. You’ll need to use a Dynamic DNS service of some sort to keep the DNS records up to date.
Your ISP or the domain registrar should have DNS numbers you can use. Else, there are many free DNS services available – google is your friend.
As stated above, if you can swing a static IP Address, do so, it will save you some hassle. Be sure to set up a firewall and block everything incoming, for a web server only. Otherwise be vary careful of what you ports you leave open, research them carefully so you are aware of what you are doing. I’ve had great fun with a home web server and others, but educate yourself. Be sure it is isolated from your home network.