First thing I noticed is that on most of the pages you're checking $_SESSION['logged'] and then suddenly on the edit page you're checking $_REQUEST['id'], as well as there being no session started on those pages.

You should probably go back over your scripts and create some kind of uniform check to see if the user is logged in, and redirect them if they're not. Perhaps a function inside one of your common includes? isLoggedIn()? Or however you want to do it.
-m