[eluser]skunkbad[/eluser]
In the actual php language, there are two ways to include other php files. There may be a CI solution, and if so, I'm sure somebody else will chime in.
#1: include '/home/~learn/php/and/you/would/not/need/to/ask/this/question.php';
#2: require '/home/~learn/php/and/you/would/not/need/to/ask/this/question.php';
You can also use _once on the end, and this makes it so that the include can only be loaded once.
include_once ''; or require_once '';
"require" is used when you want to load something, and if it fails to load the script will die. Using "include" will allow the script to keep running if it fails to load the included file.
The php manual is at php.net, and if you haven't read it, you really should. It's very awesome.