Arranging selected files through Open File dialog in treelist control devexpress wpf

Question

I'm able to select files through through folder browser dialog but I need to show the selected file in treelist control (Note: I'm using WPF and devexpress controls). How can I achieve this? Please check the image:

*******************Code**********************

 private void loadFilePst ()
    {
        try
        {
            Microsoft.Win32.OpenFileDialog dlg = new Microsoft.Win32.OpenFileDialog();
            dlg.DefaultExt = ".pst";
            dlg.Filter = "PST Files(*.pst)|*.pst";
            Nullable<bool> output = dlg.ShowDialog();
            if (dlg.ShowDialog() != true)
                return;
            using (Stream stream = dlg.OpenFile())
            { 

            }
            //if(output == true)
            //{
            //  stgPath = dlg.FileName;
            //  string fileName = dlg.FileName;
            //  treePstSelect.Visibility = Visibility.Visible;
            //}
            //System.Windows.MessageBox.Show("Hola");
        }
        catch(Exception ae)
        {
            System.Windows.MessageBox.Show(ae.Message);
        }
    }