If you want to run a webserver (httpd) on your computer, then generally you have to do "port forwarding" of ports 80 and 443 on your router/DSL_modem to your computer hosting the server. You router may have an internal address like 192.168.1.1 and your computer 192.168.1.20. Now the ISP will give the modem an external IP address like 72.14.205.146
While checking if the port forwarding works, a common mistake is to point your browser as http://72.14.205.146
This generally won't work. You have to be outside your local LAN. So a convenient way is to use a (anonymizing) proxy like http://www.zend2.com/index.php to check if http://72.14.205.146 leads you to your webserver.
* Of course any firewalls on your computer should allow incoming connections on ports 80 and 443.
* If you don't have a fixed IP address you can setup an account on noip.com
