如何让时间走起来?

请教各位高手,我是个新人,我这样写完如何让时间在窗体里走起来? DateTime now = DateTime.Now;
Label5.Text = now.ToString( "yyyy年M月d日 "); 　
Label6.Text = now.ToShortTimeString();
Label7.Text = now.ToString( "dddd ");