create sign up form for google group

here is javascrip/html code how to do it:

<script type="text/javascript">
   function msgbox() {   alert("An Invatation has been sent to " + _gel("emailconf").value 
+ ". You will have to confirm the email invitation to join and recieve future emails. 
You can opt out of our group at anytime using the Unsubscribe link in the email."); }
</script>

    Sign up with our google group to receive [product] updates or ask questions.
  <form action="http://groups.google.com/group/whiterocksoftware/boxsubscribe" id="formconf" onsubmit="msgbox()">
  Email: <input type=text name=email id="emailconf">
   <input type="submit" value="Subscribe">
</form>