I am coming from the Zend Framework background and In Zend framework I define all access permission in one file and call them in bootstrap before the controller is called , and check the user has got permission to run it.
I am looking for that kind of code sample. Please post if you have any sample code
Simpleauth uses a config file. Default config files are provided in the package.
You need to copy the auth.php config file to app/config, and configure it for simpleauth. Then copy the simpleauth.php to app/config too. In there you'll find examples on how to define groups, roles and permissions.
Once done, run the migrations to create the users table (make sure you configure your db first!):
php oil r migrate --packages=auth
You can check the docs for the methods available. There a controller example at http://docs.fuelphp.com/packages/auth/examples/auth.html. It's from a live app, so you can't copy and paste it, but it should give you enough pointers on how to make your own auth controller.