title: how to get or create role in yii
body: <p>I am a newbie to yii. I have stuck my mind with yii-tutorials for creating roles in yii. but I am not getting how can I create role in yii. means I want to create two roles <code>admin</code> &amp; <code>staff</code> and I want to give different priviliage to them.<br/>
  I have created a <code>role</code> in user table, but I am not getting that how can I create a role and can assign priviliages to them, please help me guys</p>
  
  <p>Thanks in advance</p>