PHP Code:
$forumdata =& datamanager_init('Forum', $vbulletin, ERRTYPE_ARRAY);
$forumdata->set('title', 'NAME OF NEW FORUM');
$forumdata->set('description', 'FORUM DESCRIPTION');
$forumdata->set('link', '');
$forumdata->set('displayorder', 1);
$forumdata->set('parentid', 12);
$forumdata->set('daysprune', -1);
$forumdata->set('defaultsortfield', 'lastpost');
$forumdata->set('defaultsortorder', 'desc');
$forumdata->set('showprivate', 0);
$forumdata->set('newpostemail', '');
$forumdata->set('newthreademail', '');
$forumdata->set_bitfield('options','moderatenewpost', 0);
$forumdata->set_bitfield('options','moderatenewthread', 0);
$forumdata->set_bitfield('options','moderateattach', 0);
$forumdata->set_bitfield('options','styleoverride', 0);
$forumdata->set_bitfield('options','canhavepassword', 0);
$forumdata->set_bitfield('options','cancontainthreads', 1);
$forumdata->set_bitfield('options','active', 1);
$forumdata->set_bitfield('options','allowposting', 1);
$forumdata->set_bitfield('options','indexposts', 1);
$forumdata->set_bitfield('options','allowhtml', 0);
$forumdata->set_bitfield('options','allowbbcode', 1);
$forumdata->set_bitfield('options','allowimages', 1);
$forumdata->set_bitfield('options','allowsmilies', 0);
$forumdata->set_bitfield('options','allowicons', 0);
$forumdata->set_bitfield('options','allowratings', 0);
$forumdata->set_bitfield('options','countposts', 1);
$forumdata->set_bitfield('options','showonforumjump', 1);
$forumdata->set_bitfield('options','prefixrequired', 1);
$forumdata->set('styleid', -1);
$forumdata->set('imageprefix', '');
$forumdata->set('password', '');
$forumdata->save();
unset($forumdata);
^^Thats how you create a new forum in code, if you are unsure of what an option is, look at the forum manager for creating new forums and see the descriptions next to those options.