[xwiki-users] Belletin Board Application - Email users

I'd like to add the functionality of emailing users who post to a thread that a new post has been created. I have no idea of the level of complexity of this is, but I would greatly appreciate it if someone could at least point me to where I would need to add the code. I've looked at BBCode.TopicClassSheet, which has the form for submitting a new post, but I get stumped from there. The action for the form is $doc.getURL("ojbectadd") which returns a value of "/xwiki/bin/objectadd/BBCode/TopicClassSheet". I'm just not sure how to get to the "objectadd" so it can be edited. Any help is much appreciated. Lenny