How can use timer control in c#

Design part

Today we are going to something new about timer control.Timer control is very interesting and so easy. so don't be afraid.
You can show on screen 00:00:00. It is label and 3 button control and last one is used timer control. Timer control is not show on run-time program, it control show on below form.
Now Design phase is ready and discuss about coding part.

Coding part - 

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace timerprogram
{
    public partial class Form1 : Form
    {
        int hr, min, sec;            // declare variable
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            label1.Text = hr.ToString("00") + ":" + min.ToString("00") + ":" + sec.ToString("00");  
        }

        private void btnstart_Click(object sender, EventArgs e)
        {
            timer1.Start();  
        }

        private void btnpause_Click(object sender, EventArgs e)
        {
            timer1.Stop();
        }

        private void btnreset_Click(object sender, EventArgs e)
        {
            timer1.Stop();
            hr = 0;
            min = 0;
            sec = 0;
            label1.Text = hr.ToString("00") + ":" + min.ToString("00") + ":" + sec.ToString("00");
        }

        private void timer1_Tick(object sender, EventArgs e)      //important timer used tick event.
        {
            if (sec < 59)
            {
                sec = sec + 1;

            }
            else
            {
                sec = 0;
                if (min < 59)
                {
                    min = min + 1;

                }
                else
                {
                    min = 0;
                    hr = hr + 1;

                }


            }
            label1.Text = hr.ToString("00") + ":" + min.ToString("00") + ":" + sec.ToString("00");
        }
    }

}