$("nombre_usuario").onfocus = function(){
	if(this.value == "Your name"){
		this.value = "";
	}
}
$("email_usuario").onfocus = function(){
	if(this.value == "Your e-mail"){
		this.value = "";
	}
}
$("email_amigo").onfocus = function(){
	if(this.value == "Your friend's e-mail"){
		this.value = "";
	}
}
$("form_tell_a_friend").onsubmit = function(){
	var campo = $("nombre_usuario");
	if(campo.value == "" || campo.value == "Your name") {
		alert("Your name is required.");
		campo.style.background = "#E9D7D6";
		campo.focus();
		return false;
	}
	var campo = $("email_usuario");
	if((campo.value.indexOf(".") == -1) || (campo.value.indexOf("@") == -1)) {
		alert("Your e-mail is required.");
	    campo.style.background = "#E9D7D6";
	   	campo.focus();
	   	return false;
	}
	var campo = $("email_amigo");
	if((campo.value.indexOf(".") == -1) || (campo.value.indexOf("@") == -1)) {
		alert("Your friend's e-mail is required.");
	    campo.style.background = "#E9D7D6";
	   	campo.focus();
	   	return false;
	}
	return true;
}