i figured it out:

#!/usr/bin/perl 
use HTTP::Cookies::Netscape;
use LWP::UserAgent;
use LWP::Simple;
my $browser = LWP::UserAgent->new( );
$cookie = HTTP::Cookies::Netscape->new(
        file => "$ENV{HOME}/nettby/cookie",
        autosave => 1
);

$browser->agent("Mozilla/4.0");
$browser->cookie_jar($cookie);
        my $response = $browser->post("http://www.nettby.no/sb_login.p
+hp", {
                 "email" => "user",
                "password" => "pass",
        });
                my $content = $response->content; 
                print $content;
$side = $browser->get ("http://www.nettby.no/user");
$site = $side->content;
print $site;
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