After I changed the line timer.Tick += new EventHandler(timer_Tick); to timer.Tick += timer_Tick; it still gives an error which is No overload for 'timer_Tick' matches delegate 'System.EventHandler'namespace App3

{

public sealed partial class MainPage : Page
{
    public MainPage()
    {

        this.InitializeComponent();

    }
    private int myCount;
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        DispatcherTimer timer = new DispatcherTimer();
        timer.Tick += timer_Tick;
        timer.Interval = TimeSpan.FromSeconds(5);
        timer.Start();

    }


    protected override void OnNavigatedFrom(NavigationEventArgs e)
    {
        base.OnNavigatedFrom(e);
    }

    private void Btm_Click(object sender, RoutedEventArgs e)
    {
        App3.timer.Start();
    }

          private void timer_Tick(object sender, EventArgs e)
    {
        myCount++;
        Label.Text = myCount.ToString();
    }