Well, firstly you have to make sure that port 80 is forwarded to computer, where you want to host the server. That way all incoming requests are directed to server. So find out exact model of your router and follow instructions appropriate to it. Quite many step-by-step guides have been given @
PortForward.com.
It isn't complicated, most routers can be accessed from browser and in this case it's just few clicks and typings.
And ofcourse, in order for visitors could see anything at all, you have to set up [b]Apache[/u] and PHP. As i can see, you have installed some x-in-1 package. I can't say how good or bad scenario Apache Friends is, because i don't have any experiences with it. In this category i can only suggest Appserv, which played out the best it could have. Still i prefer installing Apache, PHP, MySQL and all needed web-server software separately and then integrate them.
If everything seems to be okay and you can see corresponding welcome page when inserting localhost to your address bar, it's time to share out your IP and kick some ass in front of your friends.
/ 
