if you just want to add a links page you can do it like this:

If your plugin is for administrators only, the filename must have the prefix "AP_". If it is for both administrators and moderators, use the prefix "AMP_".

create a test php page called AP_Hello_World.php Place this code into the page and put the page into the plugins folder and you are done:

<?php
// Make sure no one attempts to run this script "directly"
if (!defined('PUN'))
    exit;

// Tell admin_loader.php that this is indeed a plugin and that it is loaded
define('PUN_PLUGIN_LOADED', 1);

// Display the admin navigation menu
generate_admin_menu($plugin);

echo "Hello World";

8. Plugins must be released under the GNU General Public License or
    a GPL compatible license. Copy the GPL preamble at the top of
    this file into your plugin script and alter the copyright notice
    to refrect the author of the plugin (i.e. you).

I have a gaming cms that i programmed in php. I would like to integrate my cms with punbb. Am I allowed to protect my code (encryption) as long as I do not encrypt any of the punbb coding?