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

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;