Martha:

Here's a basic script to pop open a window:

<script language="JavaScript"><!--
window1=window.open('test1.html','messageWindow1','scrollbars=yes,width=175
,height=300')
//--></script>

Here's a link to a great FAQ on windows in JavaScript:

http://www.irt.org/script/window.htm

On your page, the button would run a function to:

     pop-open the application window, to a predetermined size, with the
     various options available (i.e., toolbars=no)
     reload the login window - to say something like: "This page may be
     closed" or something.