Could you explain a lot more than that(Maybe even post the map)?
Are you having trouble trying to figure out the triggers for adding a new hero?
Are you having trouble trying to fugure out an idea to add a new hero?
Are you trying to do it the way where a unit goes on a beacon and then a hero is created?
Your question is really broad that if I were to answer your question in every way I interpreted it, I'd have to publish my own book.