If you only know the basics, then you might be able to do it yet.
Its not hard to do.
Browse the table of members and take note of how the password looks, if it looks like "password" youre ok, if it looks like "5thYTyhsst45yw4y7wiai8t4ag-13tawgagd" then its encrypted.
Then look through the code for the board, namely the script that creats a user account, and thus encrypts the password
look for a line similar to this
$enc_pass = md5($password);
that would mean they used md5 encryption, which is about a 99% possibility they did..
so in scripts you write.
have a form that asks for a username and a password
do the same thing to the password they enter, in this case,
$enc_pass = md5($password);
then check their username and the encoded password against the inivison board member table, and if it exists, youre good to go...
Maybe you can even just streal the boards login script completely and use it wherever you need to
you wont get me to write an entire script for you