you're gonna have to be more specific first of all so that we know what you're talking about. Such as, are you hooked up through a router? Straight to a dsl modem? etc
Secondly, You probably should learn some of the basics of networking and the internet before asking this question...
But the short answer is: if your computer is connected directly to the internet (it's hooked up straight to the cable/dsl modem or you have dialup), you should be able to go to
http://your.ip.address.here and it will pull up your site.
If you're connected to the net through a gatway or router (and if you are you will probably have a 192.168.1.x ip) then you will not be able to access your computer from the outside world without telling your router to forward port 80 from your computer. So...