How to upload image using CkEditor and Rails

I'v installed this https://github.com/tsechingho/ckeditor-rails lib into my Rails application. I would like to use CkEditor image upload functionality, but i'dont know how to write the backend logic, how to handle request, save file and send a response back to CkEditor to display uploaded image.

The CkEditor's configuration is the following:

  CKEDITOR.replace( 'editor1', {
      language: 'en',
      filebrowserImageUploadUrl : "/upload",
      filebrowserUploadUrl : "/upload",
  });

Rails function

def upload
  @func_num = params["CKEditorFuncNum"]
  @ck_editor = params["CKEditor"]

  render :layout => false
end