在Yii演示登录的帮助下为Web应用程序设置新的登录

Question

HI i have a perfectly(configured) working yii login system in its demo application, currrently i dont have much of idea on how to use its login functions( what are the exact scripts or functions to be called ) for my seperate web application, can any body tell me how to place yii directory on my web application and how to call its login functions to use it on my web application

i beleive that protected/useridentity script could do be a major script in this process, therefore following is the autheticate() function of it,

$user = tusers::model()->findByAttributes(array('username'=>$this->username));
            if ($user===null) { // No user found!
            $this->errorCode=self::ERROR_USERNAME_INVALID;
            } else if ($user->password !== ($this->password) ) { // Invalid password!
            $this->errorCode=self::ERROR_PASSWORD_INVALID;
            } else { // Okay!
            $this->errorCode=self::ERROR_NONE;
            // Store the usertype in a session:
            $this->setState('usertype', $user->usertype);