My update on this...
I have added forums to the table 'forum'
I have updated the parent ID's, descriptions etc of each of the forums that I've added.
I believe I now have to update the datastore which is
basically a series of records in an serialized form that has information about the forums and its permissions. (this was the advice vb.com gave but I can find no documentation about how to do this, and I know I'm gonna mess it up unless I get help

- especially how to do it safely)
They also said it would be in your best interested to look at
http://members.vbulletin.com/api. In particular the Datamanager class for Forums. But this is just mumbo jumbo to me... is there an idiots guide or can anyone give me good direction on this for a start point.
Any help here is much appreciated - I'm trying to save myself over 100 hours of adding and updating forums - please help