I've just been given the task of being the administrator for my organizations message board and I wanted to know how/if? I could creat a private forum within the MB that only assigned users can access?
Yes you can have a private message board. You need to first turn on private forums in the admin section > feature configuration.
Then when you create a forum you can set it to allowed members only. You can place any member you want in that forum and only they will be able to see it an access it.