First off, make sure that Apache is installed...
rpm -qa | grep apache
...or...
rpm -qa | grep httpd
Next, locate the httpd binary using the locate command...
locate httpd
You may have to update the locate database by running 'updatedb' before running locate.
Run the following to see if Apache is compiled with PHP support...
/path_to_httpd -l
You can start Apache with this command...
service apache start
...or...
service httpd start
...I'm not sure if the package is called httpd or apache. I think older versions called it apache and newer versions label it as httpd.
ChrisP