My code is
<?php if(extension_loaded(‘gd’)): ?>
                <div class="field">
                        <?php echo $form->labelEx($model2,'verifyCode'); ?>
                        <div>
                        <?php $this->widget('CCaptcha'); ?>
                        
                        <?php echo $form->textField($model2,'verifyCode'); ?>
                        </div>
                        <?php echo $form->error($model2,'verifyCode'); ?>
                </div>
<?php endif; ?>
controller code is :
public function init(){
	// import class paths for captcha extended
	Yii::$classMap = array_merge( Yii::$classMap, array(
		'CaptchaExtendedAction' => Yii::getPathOfAlias('ext.captchaExtended').DIRECTORY_SEPARATOR.'CaptchaExtendedAction.php',
		'CaptchaExtendedValidator' => Yii::getPathOfAlias('ext.captchaExtended').DIRECTORY_SEPARATOR.'CaptchaExtendedValidator.php'
	));
}
site controller code is
‘captcha’=>array(
			'class'=>'CCaptchaAction',
                            'class'=>'CaptchaExtendedAction',
			'backColor'=>0xFFFFFF,
		),