Instead of writing to a file, write to STDOUT (or leave the filehandle out, since that's the default).

Or, comment out your open and close statements, remove the OUTPUT filehandle from your print statement, and add this:

print "Content-type: text/html\n\n";
[download]

before writing any other output.

Put the script in your web server's cgi-bin directory, make it executable and load it from a browser.

That should get you started.