I want to increase values on timer tick event but it is not increasing don\'t know what I am forgetting it is showing only 1.
Generally speaking it is not a good practice to store values inside of views (such as asp.net page). It could be overwritten each time the request is sent.
You could store your data elsewhere:
public static class StaticDataStorage
{
public static int Counter = 0;
}
And use it:
protected void Timer1_Tick(object sender, EventArgs e)
{
StaticDataStorage.Counter++;
Label3.Text = StaticDataStorage.Counter.ToString();
}