<script type="text/javascript" src="http://jqueryjs.googlecode.com/files/jquery-1.3.2.min.js"></script> 
<script type="text/javascript"> 
$(document).ready(function() { 
  $('#divsecici').change(function() { 
    $ths = $(this); 
    $id = $ths.find('option:selected').val(); 
    $.ajax({ 
        url: 'fikstur/'+$id+'.php' 
    }).done(function(msg) { 
        $('#fiksturgoster').html(msg); 
    }); 
    return false; 
  }); 
}); 

</script> 
<?php 

echo '<select id="divsecici">'; 
echo '<option value="0">Hafta Seçin</option>'; 
for($a=1;$a<35;$a++){ 

echo '<option value="'.$a.'">'.$a.'. Hafta</option>'; 

} 
echo '</select>'; 

echo '<div id="fiksturgoster"></div>'; 

?>
Buyurun hocam, ben yanlış okumuşum