timer!

[Techno]

Hi there.

I am making a simple countdown app. i have almost done it but instead of the mins and seconds going down, it goes up. how can i make it go down?

DateTime currentTime = new DateTime();
			
			string hourNows = DateTime.Now.ToString().Substring(11, 2);
			string minNows = DateTime.Now.ToString().Substring(14, 2);
			string secNows = DateTime.Now.ToString().Substring(17, 2); 
			int hourNow = Int32.Parse(hourNows);
			int minNow = Int32.Parse(minNows);
			int secNow = Int32.Parse(secNows);
			
			int theHour = Int32.Parse(tc.EventTimeInput.Text.Substring(0, 2));
			int theMin = Int32.Parse(tc.EventTimeInput.Text.Substring(3, 2));
			int theSec = Int32.Parse(tc.EventTimeInput.Text.Substring(6, 2));
						
			int theSecCalc = secNow - theSec;		
			int theHourCalc = theHour - hourNow;			
			int theMinCalc = minNow - theMin;

			if(theHourCalc == 0 || theHourCalc < 0)
			{
				theHour = 0;
				hourNow = 0;
				theHourCalc = 0;
			}
			else if(theMinCalc == 0 || theMinCalc < 0)
			{
				theMin = 0;
				minNow = 0;
				theMinCalc = 0;
			}
			else if(theSecCalc == 0 || theSecCalc < 0)
			{
				theSec = 0;
				secNow = 0;
				theSecCalc = 0;
			}


			TimeDisplay.Text = theHourCalc + ":" + theMinCalc + ":" + theSecCalc;