Here i am writing code how to add option of theme change and layout change in your website.

Below are the steps you have to follow for this

• Make Layout for each (i.e left,top,right)
• Make Css for each(as per your choice)
• Create a folder named theme and put all yor layout and other file for each theme respectivley
• In Css directory create directory for each theme and put all your css and js file in respective directory

Make table named theme where each theme name has its themeID,name ¶

In Layout

<tr>
<td>
<table><?php echo CHtml::beginForm(); ?>
<tr><td>
<?php echo CHtml::label('Theme','Theme',array('class'=>'form-label')); ?></td></tr>
<tr><td>
<?php echo CHtml::dropdownlist('themeID', 'themeID',array(''=>'--Select--') 
+CHtml::listData(Theme::model()->findAll("status = 'A'",array('order' => 'theme_name',)), 'themeID', 'theme_name'),array('class'=>'span2 text','onchange'=>'this.form.submit();'));?>
</td></tr>  
<?php echo CHtml::endForm(); ?>
</table> </td>
<td><table>
<?php echo CHtml::beginForm(); ?>
<tr><td><?php echo CHtml::label('Layout','Layout',array('class'=>'form-label')); ?></td></tr>
<tr><td> 
<?php echo CHtml::dropdownlist('layoutID', 'layoutID',array(''=>'--Select--') +CHtml::listData(MenuLayout::model()->findAll(array('order' => 'layout_name',)), 'layoutID', 'layout_name'),array('class'=>'span2 text','onchange'=>'this.form.submit();'));?>
</td></tr>
<?php echo CHtml::endForm(); ?>
</table> </td>
</tr>


In Controller

public $theme;
        
        public function init()
        {
           $this->userID=Yii::app()->user->id;
            if(empty($this->userID)){
                $this->redirect(Yii::app()->homeUrl);
            }
            
            Yii::app()->theme = Yii::app()->session['theme']; 
            if(!empty(Yii::app()->session['layout'])){
            Yii::app()->layout = Yii::app()->session['layout'];
            }
            else{
                Yii::app()->layout = '//layouts/adminColumn';;
            }
            }
public $layout;