So, now I would like to use the hook system. Unfortunately I don't get how to do that. I have no clue where to start, reading the docs/hook_system.html doesnt help me getting further. My problem is to understand where I do include what.
Lets say I have my board in <docroot>/phpbb/index.php and another application in <docroot>/mysite/index.php
For instance, if I want on that <docroot>/mysite/index.php a userlogin field, what uses phpbb for registering the users, what does my index.php have to include so that it will use phpbb's userauth via phpbb_user_session_handler();?
Another thing I want to solve is having my mysite's menu on the phpbb page always. There the $template->display hook gets my attention. Now where (which .php file actually) do I implement my function what puts the mysite's menu into the phpbb template?