Default grouping in RadGridView

Hi!

 I use GridView for displaying objects such as:

 class Detail {

     string Name

     string Value

     string DetailGroup

}

 I create collection and bound GridView ItemsSource to it. In gridView i create 3 columns for each property. Then i start my application I want to the default group was by DetailGroup property. I use GroupingDescriptor, but i don't understand, how can i connect it with My DetailGroupColumn or how to bing it to the Collection property (DetailGroup).

 Will be grateful for help, I hope somebody had such problem.