ahhh... A web server on your computer... I remember my first server...
First things first... What kind of connection do you have?!? A 56k ain't gonna server anything beside a very small text file...
If you have Pro you just need to install IIS... IIS6 which comes with XP is very nice and easy to use... If you have home then you'll have to get a third party webserver...
Then you need a way to let people find your computer... You need a redirector... I use DNS2Go... Very good, very reliable...
That's all ther is to it...
Keep in mind that letting people in to your computer is a security risk... The level of that risk depends on whos looking for your site... If it's family or friend, nothing to worry about... General traffic and you better lock this up tight...
Also bandwidth concerns,,, Even with a dsl or cable connection you will notice when someones DLing or on your site...