How to Set a TimeOut for a windowsforms(C#) quiz Application

private void Form1_Load(object sender, EventArgs e)
    {
        Timer MyTimer = new Timer();
        MyTimer.Interval = (20 * 60 * 1000); // 20 mins
        MyTimer.Tick += new EventHandler(MyTimer_Tick);
        MyTimer.Start();
    }

    private void MyTimer_Tick(object sender, EventArgs e)
    {
        MessageBox.Show("The form will now be closed.", "Time Elapsed");
        this.Close();
    }