c# windows application increment time from 00:00:00

hi,
i have some problem with increment timer time will start from like this 00:00:00 after it will increment 00:00:01,00:00:02
i have create code :
 private void exam_Load(object sender, EventArgs e)         {             TimeSpan time = new TimeSpan(0);             time += TimeSpan.FromSeconds(1);             this.Timertext.Text = string.Format("{0:D2}:{1:D2}:{2:D2}", time.Hours, time.Minutes, time.Seconds);                      }
but the output is 00:00:01 after its stop. need some help thanks.