function changeTab(id)
{

       document.getElementById("Tab1Nav").className = "tabOff";
    document.getElementById("Tab2Nav").className = "tabOff";
    document.getElementById("Tab3Nav").className = "tabOff";
    document.getElementById("Tab"+ id +"Nav").className = "tabOn";
    
    document.getElementById("Tab1").style.display = "none";
    document.getElementById("Tab2").style.display = "none";
    document.getElementById("Tab3").style.display = "none";
    document.getElementById("Tab"+ id).style.display = "block";
    
    
}