There are a number of ways do to this but basically you will need to be running a Server Application. To name a couple there is apache and XP Pro has IIS built right in.
What operating system do you have? XP Home or XP Pro or something else...
Well please do some additional research on security but here is the basics..
Make sure you have the XP Pro Installation Disk in your CD/DVD drive and then
GOTO
Start/ControlPanel
Add Remove Programs
Add Remove Windows Programs
Scroll Down and Check Internet Information Services
Click Details
Check Word Wide Web Services
and click OK
1st thing off the bat you want to make sure that PORT 80 is opened up on your firewall.
If you are using a ROUTER configure your machine to use a static IP address assigned from the router. Then Forward PORT 80 to your PC's IP address...
Create a file called index.html and put it in the wwwroot folder and thats your Home Page... Simple as that!
Of course there is all kinds of other things you can do as well so do some reading and research on Internet Information Services or IIS
On Another Note if you are using a DYNAMIC IP from your ISP then you will want to either
A.) Obtain a STATIC IP (Usually there is a fee) from your ISP
or B.) Sign up at www.dyndns.com and create a Dynamic DNS account and register a site name to access your site...
few questions >.< how can I configure my comp to have a static IP address assigned from the routher and how can I forward port 80 to mi IP address. And what about the wwwroot folder? do Ijust create a folder with the name of the adress ??