Imap Problem i want to check if the message is not seen

i'd like to know which message i had not been seen, so i searched the manual and fid 2 flags says Unseen == 'U' || Recent == 'N' mean.

but i don,t understand what does Unseen == 'U' || Recent == 'N' mean(what he mean by flags)?

i want to check if the message is not seen, so how to do that?

i tried

$inbox = @imap_open("{mail.mysite.com:110/pop3}", "".$_SESSION['SESSION_USER_NAME']."+".$_SESSION['SESSION_MAIL_HOST']."", $_SESSION['SESSION_USER_PASS']) or header("Location: error.php?ec=3");$headers = imap_header($inbox, $x);if($headers->Unseen == 'U' || $headers->Recent == 'N')

Maybe you could explain your problem more clearly.. I really can't do anything with this..