You can use post, or get in your form. And then use request.getParameter("parameter_name") to extract the value. That's how you pass querystring from a form to the page which process the form.
Other method to pass parameters including use session.
Use session.putValue("Session_vbl_Name", object) to put the value into a session vbl in one page and you can retrieve in any jsp/servlet page inside your application. To do that, just use session.getAttribute("Session_vbl_name").
I hope this helps.