Countdown timer in asp.net

Question

i created a count down timer, but i am not getting how to show hour also it just showing seconds and minutes. Can any one guide me please...

 

My code is:

 

protected void Page_Load(object sender, EventArgs e)

{

if (!SM1.IsInAsyncPostBack)

{

Session["timeout"] = DateTime.Now.AddSeconds(120).ToString();

}

}

protected void timer1_tick(object sender, EventArgs e)

{

if (0 > DateTime.Compare(DateTime.Now, DateTime.Parse(Session["timeout"].ToString())))

{

lblTimer.Text = string.Format("Time Left: 00:{0}:{1}",

((Int32)DateTime.Parse(Session["timeout"].ToString()).Subtract(DateTime.Now).TotalMinutes).ToString(),

((Int32)DateTime.Parse(Session["timeout"].ToString()).Subtract(DateTime.Now).Seconds).ToString());

}

else

{

timer1.Enabled = true;

}

}