[eluser]johnwbaxter[/eluser]
I think you should go and have another look at the user guide, this is explained there and there is demo code too thankfully!
However you don't need to use require, you could move your users.php into a library then you can simply do this:
$this->load->libary(users)
The great thing about CI is the use of libraries IMHO, i'm constantly trying to move everything into a library to minimise the the amount of code in my controllers.