To start with you need to download the latest stable release of CKeditor.
Extract the downloaded file and place the ckeditor/ folder in your applications webroot directory. (beside "protected" and "css" and other directories)
First declare an attribute to store the file name in the model class (either a form model or an active record model).
Also declare a file validation rule for this attribute to ensure a file is uploaded with specific extension name.
This little tutorial explains a way how you can retrieve more parameters from Yii::app()->user by adding a component that extends CWebUser and retrieves the user information from database table named User.
The purpose of this post is to let anyone quickly find how to accomplish a configuration task, and list here all the posibilities of the config.php file and also link to pages that explain how is each thing implemented.