You should not have to add global.php since it is already called at the top of user.php (where the hook useradmin_update_save is located). I have a form on my site which creates a new thread, and I basically follow what is done in newthread.php - define all the $newpost variables and then build_new_post (which all builds a new thead when called that way). Look in that script and see if it help you out.