[Zope] roles & permissions newbie question

I know this has been done, but I don't know how to do it myself. I'm trying to write a html page where some parts gets displayed only if the user has logged in. If the person is not logged in, it should display some generic text, with perhaps a "login" button somewhere. I'm also trying to do this from an external method. For one thing, I'm not sure if I need to add another role or another permission. I can't seem to be able to add another permission, I only see the ability to add a user role. So I tried that, and used SecurityManager.validate(). But it forces you to login, whereas I want a more passive approach. Thanks, Albert