La vista en Usuarios:
<div class="usuarios form">
<?php echo $this->Session->flash('auth'); ?>
<?php echo $this->Form->create('Usuario'); ?>
<fieldset>
<legend>
<?php echo __('Please enter your username and password'); ?>
</legend>
<?php echo $this->Form->input('username');
echo $this->Form->input('password');
?>
</fieldset>
<?php echo $this->Form->end(__('Login')); ?>
</div>
