[kh99]

If you're including vbulletin's global.php (or you don't mind including it), then you can use the user datamanager. If you look at admincp/user.php around line 979 (the section that starts with if ($_POST['do'] == 'update')), then you can see how it's done when you add a user via the admincp.

If you don't want to use the vbulletin code you need to figure out what to write to the database. I think you might just have to insert a row in the user table, get the userid of the inserted row, then add rows to the userfield and usertextfield tables. But to make sure you're doing everything you need to do you'd have to study the user datamanager (in inlcudes/class_dm_user.php).

I suppose you could also use a test forum and dump the database, add a user then dump it again and see what's changed.