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)
For those who feel, the Controller->accessRules() or RBAC (Role-Based Access Control) is too complicated or doesn't want the username(s) to be hard-coded in accessRules(), here is a very simple, easy-to-implement solution.
This wiki is a step-by-step example explaining how the controller, model and the view's CGridView work together. It explains simple things - as well as more complex things that you will anyway quickly have to know. So, even if you don't use dynamic gridviews, take a morning off and thoroughly work through this tutorial. It should save you lots of struggling.