Script to create new thread followed by a new post

[TeamDevotion]

So I have a page where a new thread is created via the following script.

// ################# start new thread ###############################
		// Create a new datamanager for posting 
		$threaddm =& datamanager_init('Thread_FirstPost', $vbulletin, ERRTYPE_ARRAY, 'threadpost');

		// Set some variable and information 
		$forumid = 59; 
		// The user id of the person posting
		$user = htmlspecialchars_uni( fetch_userinfo($userid) ); 
		$title = $user['username'] . "'s " . $year . " " . $make . " " . $model . " [" . $color . "]";                                           // The title of the thread
		$pagetext = addslashes("Testing mic check 1 2");                                      // The content of the thread
		$allowsmilie = '1';                                                             // Are we allowing smilies in our post
		$visible = '1';                                                                 // If the post visible (ie, moderated or not)

		// Parse, retrieve and process the information we need to post 
		$foruminfo = fetch_foruminfo($forumid); 
		$threadinfo = array(); 
		

		$threaddm->set_info('forum', $foruminfo); 
		$threaddm->set_info('thread', $threadinfo); 
		$threaddm->setr('forumid', $forumid); 
		$threaddm->setr('userid', $userid); 
		$threaddm->setr('pagetext', $pagetext); 
		$threaddm->setr('title', $title); 
		$threaddm->set('allowsmilie', $allowsmilie); 
		$threaddm->set('visible', $visible); 

		// Lets see what happens if we save the page 
		$threaddm->pre_save(); 
		if(count($threaddm->errors) < 1) { 
			// Basically if the page will save without errors then let do it for real this time
			$threadid = $threaddm->save(); 
			unset($threaddm); 
		} else { 
			// There was errors in the practice run, so lets display them 
			var_dump ($threaddm->errors); 
		} 
		// ################# end new thread###############################

Now, i want to add a post to the thread i just created but am unsure how. The post will use a different username than thread, and i already have the newly created thread ID.

I do not need information on how to extract data i just need the syntax to make a new post in an already existing thread.