[Zope] Login track

Hello, I have my own information system on Zope. I would like to enable users to login and do acts, what they can do (according to security settings). But I cannot track already logged users. I redirect them into login page, when they want to login. After passing the credentials, they are succesfuly logged. But if they click on the other site on my system, it shows me, that there is not logged user, but Anonymous user. Please, could you help me how to retain information who is currently logged until his logout? I would be very glad, thank you. Domco