ah the wonder of sessions! sesions variables are kept in a folder called sessions on the server and are user to keep track of variables when a user is in your site. they are destoyed when the user quts his browser.
put this code at the end of the login script, just before the script redircts the user to your page
//please correct me here guy, i alwasys screw somethin up
$logged = 1; // meaning yes of course
then put this at the beggining of every page you want to protect (or save it in a sepeate and use "require('check.php');" )
if (isset $_SESSION['logged'] && $_SESSION['logged'] ==1)
hope that helps