Err, is there any reason why you're not using CGI.pm proper? It saves you even more effort.

#!/usr/bin/perl

use strict;
use warnings;
use CGI ':all';
use CGI::Carp qw(fatalsToBrowser);

#assign variables
my $loginame= param('username');
my $p_word=param('password');

print header();
print start_html();

print "***$loginame AND $p_word***";
print end_html();
exit;
[download]

I prefer the OO version, but have not used it to keep the code looking as similar to yours as possible.