//Funcion que verifica campos del formulario vacios
function Validar(f) {
if (f.email.value=='') {
    alert("Please, write your email");
    f.email.focus();
    return (false);
    }
if (f.phone.value=='') {
    alert("Please, write your phone number");
    f.phone.focus();
    return (false);
    }
//if (f.message.value=='') {
    //alert("Please write a message");
    //f.message.focus();
    //return (false);
    //}
}