I want to make download window

how do i make download window? help me.

dhxWinsApplicationCV = new dhtmlXWindows();
dhxWinsApplicationCV.enableAutoViewport(false);
dhxWinsApplicationCV.setImagePath(“<?=$rfa;?>/images/icons/16x16/”);
dhxWinsApplicationCV.enableAutoViewport(false);
dhxWinsApplicationCV.attachViewportTo(document.body);
w1ApplicationCV = dhxWinsApplicationCV.createWindow(“image”, 20, 10, 450, 320);
window.alert() = w1ApplicationCV();
w1ApplicationCV.center();
w1ApplicationCV.denyResize();
w1ApplicationCV.setText(“Download”);
w1ApplicationCV.setIcon(“drive-download.png”, “drive-download_dis.png”);
w1ApplicationCV.attachURL(“applicationcv.php?applicationid=”+id);
}

applicationcv.php page

header(‘Content-Description: File Transfer’);
header(‘Content-Type: application/force-download’);
header(‘Content-Type: application/’.$fileext);
header(‘Content-Disposition: attachment; filename="’.basename($filename).‘"’);
header(‘Content-Transfer-Encoding: binary’);
header(‘Expires: 0’);
header(‘Cache-Control: must-revalidate, post-check=0, pre-check=0’);
header(‘Pragma: public’);
header('Content-Length: ’ . filesize($filepath));
ob_clean();
flush();
readfile($filepath);

what should i do?