how to find value from datagride in wpf

private void Window_Loaded(object sender, RoutedEventArgs e)
        {
           
            Process[] p = Process.GetProcesses();
            List<li> lst = new List<li>();
            foreach (Process ps in p)
            {
                li pp = new li();
                pp.NAME = ps.ProcessName.ToString();
                lst.Add(pp);
            }
           
            gv1.ItemsSource = lst;
        }
        public class li
        {
            public string NAME
            {
                get;
                set;
            }
        }

private void gv1_SelectionChanged(object sender, SelectionChangedEventArgs e)
       {
           MessageBox.Show(((li)e.AddedItems[0]).NAME);
       }