how to add times from two datetimepicker

Hi Shivaraj,
   If u want to calculate exact difference between two datetimepicker then on ValueChanged event u can do like this :
  
    private void dateTimePicker2_ValueChanged(object sender, EventArgs e)
        {
            DateTime date1, date2;
            date1 = Convert.ToDateTime(dateTimePicker1.Value);
            date2 = Convert.ToDateTime(dateTimePicker2.Value);
            System.TimeSpan diff;
            diff = date2 - date1;
            MessageBox.Show("Difference is Days :" + diff.Days + "  Time" + diff.Hours + ":" + diff.Minutes + ":" + diff.Seconds);
        }

Note : I have calculated difference when value changed for datetimepicker2

try this
MessageBox.Show((dateTimePicker1.Value - dateTimePicker1.Value).ToString());