Tabbing on a PHP mail form?

How to make tabbing work on my mail form?
When user wants to go from text field to text field,
what he/she need to do is just simplytab,
but it doesn’t work automatically on my form -
do I need a special code for this?

<?php
$emailku="user@yahoo.com"; // your email address to send to
$validResponse=“Thank you for your interest in our company.”; // your response message appeared in flash after sending

$regex="^([a-zA-Z0-9._-]+)@([a-zA-Z0-9-])+(.[a-zA-z0-9-]+)+$";
$email=strtolower($email);
$subjectEmail = “website mail[$name1]”;

$messageTotal = "First Name    : $name1
Last Name    : $name2

Address : $address
City    : $city
State   : $state1
Zip     : $zip


Email   : $email
Phone   : $phone



How did you hear about us? : $hear


Additional Comments? : $help


";

mail($emailku,$subjectEmail,$messageTotal,"From:$email

Reply-to: $email
“);
//add and change email to send copy to another address
//mail("myother@email.com”,$subjectEmail,$messageTotal,"From:$email
Reply-to: $email
");

print “&answer=”.urlencode($validResponse);

?>