The index view is rendered by the index action and is used to initialize the application and provide a do Template that is used for rendering on the client side. We can use it by following way : 
Yii::app()->clientScript->registerPackage('todo');

Yii has a special class named CClientScriptthat can help include scripts, CSS, and other resources in the page.
In order to include an external CSS, you can use the following code:	
Yii::app()->clientScript->registerCssFile('http://example.com/css/main.css');

application configuration parameters that can be accessed using 
Yii::app()->params['paramName']
'params'=>array(
// this is used in contact page'adminEmail'=>'webmaster@example.com',
),

We have to use the following html  form attributes : 'htmlOptions'=>array('enctype'=>'multipart/form-data')

Efficient coding with Yii implies efficient use of the gii code generator. It helps to create model,view and controller without writing codes.