[Zope] Form Variable location and persistence!

Hi, I have a input variable 'username' in a form. This form call a DTML method that call a stored procedure to check for user autorization. When the user login it will be send to a main page with a navigation frame and a main frame. The main frame will reder all modules that this user will be able to use. My problem is that I have to pass the 'username' entered in the first form to this modules selection DTML method but Zope can not find the username parameter. I have tried the examples in Chap 7 of The Zope Book but it doesn't work. Does anyone knows how to do that. How can I create persistent variable in Zope? If I need to use cookies how can I do that in Zope? TIA Regards, Ricardo