a ok grazie mille per le spiegazioni!!!

quindi devo cambiare anche qua:


[CODE]
<html>

<head>

<script>

var INSERT_USER = "Inserisci l'utente";

var INSERT_PASSWORD = "Password";

// l'elemento input prende il focus

function FocusUser()
{ frmLogin.Username.value = "";
frmLogin.Username.className = "";
}

function FocusPass()
{
frmLogin.Password.value = "";
frmLogin.Password.className = "";
}

// l'elemento input perde il focus

function BlurUser() {

if (frmLogin.Username.value == "")
{
frmLogin.Username.value = INSERT_USER;

frmLogin.Username.className = "tiepido"; }
}

function BlurPass() {
if (frmLogin.Password.value == "")

{
frmLogin.Password.value = INSERT_PASSWORD;
frmLogin.Password.className = "tiepido"; } }

// controlla validità del form

function controlla() {


if ( ((frmLogin.Username.value=="") ||
(frmLogin.Username.value==INSERT_USER)) && ((frmLogin.Password.value=="") || (frmLogin.Password.value==INSERT_PASSWORD))
) { alert("Devi inserire username e password");

} else if ( (frmLogin.Username.value=="") ||
(frmLogin.Username.value==INSERT_USER) )
{ alert("Devi inserire l'username"); }

else if ( (frmLogin.Password.value=="") ||
(frmLogin.Password.value==INSERT_PASSWORD) )

{ alert("Devi inserire la password"); }

else { frmLogin.submit(); } } function aprifinestra() {

weblink=window.open("registrati.php","registrazion e","width=600px,height=500px,left=350px,top=100px" ); }

</script>

<link rel="stylesheet" type="txt/css" href="css1.css">
<link rel="stylesheet" type="text/css" href="css_menu.css" >

<script src="fixedbackground3.js" type="text/javascript"></script> </head>

<body onLoad="fixedBackground('blackboard.jpg');"> <p align="center">

[img]titolo2.png[/img] </p> <div align="center" >

<div class="intestazione"> <div style="position:absolute;Margin-left:370px;margin-top:20px;">

<font color="white" face="eraser"size="8">HOME</font> </div>
<div style="position:absolute;margin-left:700px;" >

<form id="frmLogin" action="<?php echo $_SERVER['PHP_SELF']?>" align="right" method="POST" > <fieldset style="width:150px;" >

<legend><font color="white" face="eraser">login:</font></legend>
<input type="text" name="Username" size="20" value="Inserisci l'utente" class="tiepido" onfocus="FocusUser();" onblur="BlurUser();">


<input type="password" name="Password" size="20" value="Password" class="tiepido" onfocus="FocusPass();" onblur="BlurPass()";>


<input type="button" value="Login" onClick="controlla();"> <font color="white"><u>registrati</u></font> </fieldset> </form> </div> <div id="menu"> <ul>[*]