class AppController extends Controller {

    var $components = array('Auth', 'Session');
    var $helpers = array('Form');




}`

class UsersController extends AppController {
    var $name = 'Users';
    var $components = array('Auth');

    function login()
    {

    }
    function logout()
    {
    $this->redirect($this->Auth->logout());
    }
  }

<?php
    echo $this->Session->flash('auth');
    echo $this->Form->create('User');
    echo $this->Form->input('username');
    echo $this->Form->input('password');
    echo $this->Form->end('Login');
?>

public function login() {
    if ($this->Auth->login()) {
        $this->redirect($this->Auth->redirect());
    }
}