Тебе нужно немного изменить код под себя и всё.
using System;
using System.Windows.Forms;
namespace TempWinFormProject {
public partial class Parent : Form {
public Parent() {
InitializeComponent();
tm = new Timer();
tm.Tick += new EventHandler(tm_Tick);
tm.Interval = 1000;
}
Timer tm = null;
int startValue = 0;
private string Int2StringTime(int time) {
int hours = (time - (time % (60 * 60))) / (60 * 60);
int minutes = (time - time % 60) / 60 - hours * 60;
int seconds = time - hours * 60 * 60 - minutes * 60;
return String.Format("{0:00}:{1:00}:{2:00}", hours, minutes, seconds);
}
void tm_Tick(object sender, EventArgs e) {
if(startValue != 0) {
label1.Text = Int2StringTime(startValue);
startValue--;
} else {
(sender as Timer).Stop();
(sender as Timer).Dispose();
MessageBox.Show("BadaBoom!");
}
}
private void buttonStart_Click(object sender, EventArgs e) {
startValue = 60 * 60 * (int)numericUpDownHour.Value + 60 * (int)numericUpDownMin.Value + (int)numericUpDownSec.Value;
tm.Start();
}
}
}