Definitely look into CGI as ColtsFoot suggests. It will make your life so much easier (after you learn the basics, which shouldn't take too long). Here's a revised start to your script, which uses CGI.pm to get the query string (much, much easier and more robust):

#!/usr/bin/perl -wT

use strict;
use CGI;

my $page = new CGI;
my $in = $page->param('alpha');
[download]

And so forth. I'm not sure what you intend to do with the form or the alpha subroutine. Perhaps you could reply and shed more light on it.