I read the document, but failed to apply..
I want the sample code is applied to ckeditor
Help me please..

config.extraPlugins = 'doksoft_easy_image';

config.doksoft_uploader_url = 'path-to-ckeditor/plugins/doksoft_uploader/uploader.php'; 

config.toolbarGroups = [
    {name : 'doksoft_easy_image'}
];

console :

Uncaught TypeError: Cannot read property 'id' of undefined

toolbarGroups

only defines a buttons in the groups, not the buttons on toolbar.
To define a toolbar use this code:

config.toolbar = [
      { name: 'some_toolbar_area', items: [ 'doksoft_easy_image'] }
];

Read more about CKEditor's toolbar definition here: http://ckeditor.com/latest/samples/plugins/toolbar/toolbar.html

Thank You :D