Installing Or Changing New Theme

hello. I would like to know how to change the theme in yii. I downloaded a couple of free themes but I was not able to successfully install the theme. I tried every tutorial i saw in the internet but nothing seems to work. I installed yii in wamp. please help. thanks.

take look at the guide

http://www.yiiframework.com/doc/guide/1.1/en/topics.theming

thanks. i did it.