//Vérification du formmulaire
function validForm(TheForm) {
	if (TheForm.Prenom.value.length < 1) {
	    alert("Please enter your first name.");
	    TheForm.Prenom.focus();
        return false;
    }
    if (TheForm.Nom.value.length < 1) {
        alert("Please enter your surname.");
        TheForm.Nom.focus();
        return false;
    }
    if (TheForm.Ville.value.length < 1) {
        alert("Please enter the name of your city.");
        TheForm.Ville.focus();
        return false;
    }
    if (TheForm.Tel.value.length < 1) {
        alert("Please enter your telephone number.");
        TheForm.Tel.focus();
        return false;
    }
}