file upload process in drupal 7

     $file=false;
       $tileImageFid=0;
       $tilefile = file_load($form_state['values']['tile_image']);
       if($tilefile){
                $tilefile->status = FILE_STATUS_PERMANENT;
                file_save($tilefile);
                file_usage_add($tilefile, 'SpecialOFfers', 'SpecialOFfers', '1');
                 $tileImageFid=$tilefile->fid;
 
       }