Form validation

[[e-mail]]

DOES ANY ONE KNOW HOW TO VALIDATE THIS FORM?
case 1: if any field is not completed, display in red colour and display a text message to correct,

case 2: once is completed, display TANKS FOR SUBMIT YOUR FORM, AND REDERECT TO INDEX PAGE.

<?php 

$msg ="Name:       $_POST[name]\n";
$msg .="Email:      $_POST[email]\n";
$msg .="message:    $_POST[message]\n";
$subject = "form results";

$recipient = "[e-mail]";
$mailheaders ="reply-to: $_POST[email]";

mail($recipient, $subject, $msg, $mailheaders);
?>

THANK EVERY BODY

[ADVAD]

DOES ANY ONE KNOW HOW TO VALIDATE THIS FORM?
case 1: if any field is not completed, display in red colour and display a text message to correct,

case 2: once is completed, display TANKS FOR SUBMIT YOUR FORM, AND REDERECT TO INDEX PAGE.

<?php

$msg ="Name: $_POST[name]\n";
$msg .="Email: $_POST[email]\n";
$msg .="message: $_POST[message]\n";
$subject = "form results";

$recipient = "[e-mail]";
$mailheaders ="reply-to: $_POST[email]";

mail($recipient, $subject, $msg, $mailheaders);
?>

THANK EVERY BODY

Check this link http://www.echoecho.com/jsforms.htm, pretty good..