sounds like you are trying to type the file path directly into your browser. Is insalled on your local machine? just type http://localhost/ or if it on a remote computer http://192.168.0.5 (or what ever the ip address of the server is.)
The pages have to be in the directory that Apache is configured to serve. In Linux this is often /var/www/html. The Apache directive that defines this directory is in httpd.conf and is called DocumentRoot. So in above example in Linux it would be DocumentRoot "/var/www/html". And of course Apache server should be started. In case apache is located on the same machine as the browser, just access the page by localhost in the location as leviathan185 posted above.