php is really not hard at all to install on a server... I think you wasted your money paying for one

... but i taught myself how to program in php with the book entitled...
Sams Teach Yourself PHP, Mysql and Apache.
It's a must for anyone learning php. As far as making a game, I'm sure my website
http://www.php-gamers.com/ can help your students out by them joining the forums. It's a newly created website and this is just the type of thing I had in mind for a userbase

.
There is no special editor you need, I started out using Notepad within the accessories tab in windows. Here is a hello world using php(will not work if php is not installed on your server)
<?php
echo"Hello World";
?>
save the file as .php and it's ready.
Although recently I have switched editors to a program called Notepad++ it is very powerful+lightweight and highlights the code for you where it is easier to use.
The program can be found here..
http://notepad-plus.sourceforge.net/uk/site.htm
I hope to see you around at my forums
....
ADMIN@php-gamers.com
NOTE: Before you jump into php, you first need to know html, wich can be done in one six week period, leaving the rest of the year for php.