how to set up ckeditor with yii

i just downloaded ckeditor and want to install it with my yii application… so can any one please help me with this…

i am getting this error…

Alias "ext.ckeditor.CKEditorWidget" is invalid. Make sure it points to an existing PHP file.

thanks…

there is few extensions that integrate ckeditor with yii http://www.yiiframework.com/search/?q=ckeditor&type=extension