I have already got an app on Facebook but not sure how to automatically login a user at the entry of the app without them clicking onto the blue Login button. And the user is automatically logged out of the website (the app is running on) as soon as they leave the app but still stay logged on their facebook profile

Is there any way to do this?
Like session wise.

.. And also the app/website Facebook connect can only login when you access the app/website by the direct page rather than the app/website being used within the frame on the Facebook app page/site.