in reply to error @ line7

With CGI, you are learning an obsolescent technology. A Web program in the year 2013 looks like that: 
use strict;
use diagnostics;

my $html = <<'HTML';
<!DOCTYPE html>
<html>
    <head>
        <title>My First PSGI Script</title>
    </head>
    <body>
        <h1>This is a pretty lame Web page</h1>
        <p>Who are these perlmonks, anyway?</p>
    </body>
</html>
HTML

my $app = sub {
    return [
        200,
        ["Content-Type" => 'text/html'],
        [$html]
    ]
};

[download]
Save it as app.psgi, run it with plackup.

In Section Seekers of Perl Wisdom