<a href="yayin.php?yayin=<? echo "$id"; ?>">Yayınla</a>

$yayin= $_GET["yayin"];
$yayinla= mysql_query("UPDATE sayfa SET yayin='e' WHERE id='$yayin'");
if($yayinla){
header("Location:listele.php");
}else{
echo "İçerik Yayınlandı";
}