Hello. What is the error you are getting? Maybe you need to add
LoadModule php5_module <path>
AddType application/x-httpd-php .php
to your httpd.conf
Still, I recommend doing it this way:
apt-get install apache2 php5 libapache2-mod-php5
If that doesn't work either, give us more details and maybe show us what /var/log/apache2/error_log says.