The tabindex just specifies the order in which form elements will be traversed when the tab key is pressed.
To automatically focus the first field in the form, add this javascript code to the bottom of your page:
Code:
<html>
<body>
<form method="post" action="tUsr.asp" id="login" name="login">
<input tabindex="1" type="text" name="Usr" />
<input tabindex="2" type="password" name="Usr" />
<input tabindex="3" type="submit" value="login" />
</form>
<script type="text/javascript" lanaguage="JavaScript1.1">
<!--
document.login.Usr[0].focus();
-->
</script>
</body>
</html>