Making a browser 'pop-up' is purely a html question -- you'll probably want something like one of these:

  <form ... target="_blank">
  or
  <a href="..." target="_blank">
  or something (button, link, etc that invokes a javascript function:
  <script language="javascript">
    function makeWin {
      // you can set the dimensions,etc of the window using this.
      var win = window.open( ... );
    }
  </script>
[download]

As for creating graphs in perl, GD::Graph is probably one of the most popular packages for that.

For CGI in general, start in the "Network/CGI Programming" section of the Tutorials.