$attachment = array(
  'guid' => $fotoadresi, 
     'post_mime_type' => 'image/jpeg',
     'post_title' => $_POST['baslik'],
     'post_content' => '',
     'post_status' => 'inherit',
	 'post_parent' => $idxx
  );

$attach_id = wp_insert_attachment( $attachment, ''.seola($_POST['baslik']).'.jpg', $idxx);
$attach_data = wp_generate_attachment_metadata($attach_id, ''.seola($_POST['baslik']).'.jpg');
wp_update_attachment_metadata($attach_id, $attach_data);
add_post_meta($idxx, '_thumbnail_id', $attach_id, true);