Can you get just strait html pages to show up? If not, then you might want to re look at your httpd.conf file. Chances are that there are some configuration problems there, and it is placing the files in weird places.
If you can get regular HTML pages to show up, but not php pages, you need to check to make sure that you have php installed. You can do this by going to a command prompt and typing in:
rpm -qa php
Now if you have php installed via an rpm, which with your level of experiance, would not only be a good idea, but I would bet this is how you have it installed, you will see something like "php-4.2.3-2" show up. If nothing shows up, then you either do not have php installed, or you do not have an rpm of it installed. Either way, you need to make sure and get it installed properly.
If it does show up, then I would guess that it is something with apache. Try restarting apache. Type this in:
/etc/rc.dinit.d/http restart
If you have apache installed the default way, you will get apache to restart. Once it has restart, then you can test the php pages again. Any time you make cahnges to the httpd.conf file, you have to restart apache to get those configurations to take place.
If that does not fix it, I would suggest uninstalling php and reinstalling it via an rpm, and try and get it either from redhat, or from some place like rpmfind.net.
If that does not fix it, your going to have to give us more details then what you have provided us with here. Sorry if this all does not work...