1. pls make sure your ISP allow outside people to access your computer via port 80. If not, change your port.
2. ASSUMING THAT YOU CONFIGURE YOUR PORT PROPERLY, you can config your httpd.conf <virtualhost> directive to accept incoming connection. (Pls go google on how to config this directive...)
3. Once you setup your virtualhost directive, you can ask your friends to try to access your website, coz some router may not allow loopback connection (i.e. when you type your website address in IE/Firefox, you cannot access your website, but other people can access it...)
4. Fix all errors that occur, and if you don't know how to fix it, pls post here. We can try to solve your prob. :>
Hope it helps.