refer this link for uploading
  	

http://php-mysql-javascript-css.blogspot.com/

for files downloading you can use headers .

<?php
// We'll be outputting a PDF
header('Content-type: application/pdf');

// It will be called downloaded.pdf
header('Content-Disposition: attachment;
filename="downloaded.pdf"');

// The PDF source is in original.pdf
readfile('original.pdf');
?>

uploading is down using html file tag and later on moved to 
the destination location.

for downloading we can use the pdf format so once we click 
on the link the pdg format of the file will be downloaded