najprościej chyba tak:
<link rel="stylesheet" href="./wb.validation.css" type="text/css">
<script type="text/javascript" src="./jquery-1.4.2.min.js"></script>
<script type="text/javascript" src="./wb.validation.js"></script>
<script type="text/javascript">
<!--
function ValidateindexForm1(theForm)
{
var regexp;
if (theForm.combo1.selectedIndex < 0)
{
alert("musisz wybrać jedną z opcji");
theForm.combo1.focus();
return false;
}
if (theForm.combo1.selectedIndex == 0)
{
alert("musisz wybrać jedną z opcji");
theForm.combo1.focus();
return false;
}
return true;
}
//-->
</script>
<script type="text/javascript">
$(document).ready(function()
{
$("#indexForm1").submit(function(event)
{
var isValid = $.validate.form(this);
return isValid;
});
$("#zmienna1").validate(
{
required: true,
type: 'text',
length_min: '1',
color_text: '#000000',
color_hint: '#00FF00',
color_error: '#FF0000',
color_border: '#808080',
nohint: false,
font_family: 'Arial',
font_size: '13px',
position: 'topleft',
offsetx: 0,
offsety: 0,
effect: 'none',
error_text: 'pole nie może zostać puste'
});
$("#zmienna2").validate(
{
required: true,
type: 'email',
length_min: '4',
length_max: '30',
color_text: '#000000',
color_hint: '#00FF00',
color_error: '#FF0000',
color_border: '#808080',
nohint: false,
font_family: 'Arial',
font_size: '13px',
position: 'topleft',
offsetx: 0,
offsety: 0,
effect: 'none',
error_text: 'wpisz poprawnie adres e-mail'
});
});
</script>
</head>
<body>
<div id="wb_indexForm1" style="position:absolute;background-color:#F0F0F0;left:120px;top:86px;width:179px;height:178px;z-index:4">
<form name="indexForm1" method="post" action="mailto:yourname@yourdomain.com" enctype="text/plain" id="indexForm1" onsubmit="return ValidateindexForm1(this)">
<input type="text" id="zmienna1" style="position:absolute;left:40px;top:34px;width:94px;height:18px;border:1px #C0C0C0 solid;font-family:Arial;font-size:13px;z-index:0" name="zmienna1" value="">
<input type="text" id="zmienna2" style="position:absolute;left:40px;top:64px;width:94px;height:18px;border:1px #C0C0C0 solid;font-family:Arial;font-size:13px;z-index:1" name="zmienna2" value="">
<div style="position:absolute;left:40px;top:94px;width:94px;height:20px;border:1px #C0C0C0 solid;z-index:2">
<select name="combo1" size="1" id="combo1" style="position:absolute;left:0px;top:0px;width:100%;height:100%;border-width:0px;font-family:Arial;font-size:13px;">
</select>
</div>
<input type="submit" id="wyslij" name="" value="Wyślij" style="position:absolute;left:40px;top:129px;width:96px;height:25px;font-family:Arial;font-size:13px;z-index:3">
</form>
ja robię to tak, tyle że oczywiście musisz mieć *.js - niekoniecznie plik jQuery