According to the discussion between Val and Ender, how did this book get to be written?

Ender decides to tell the buggers' story to the humans, so that they can forgive the buggers. Within a few weeks, basically channeling the queen's thoughts, he writes their history and notes that they forgave the humans for killing them. The hive-queen says that the two species are "tragic sisters" who killed one another, even though the queen would now welcome humans "as guestfriends." Ender signs the book as "Speaker for the Dead."

The book is published and passed from hand to hand quietly until almost everyone on Earth has read it, though no one knows the author. People begin to live by its principles, and people begin to have a Speaker for the Dead talk at their loved ones' funerals, to "say what the dead would have said, but with full candor, hiding no faults and pretending no virtues." It becomes one of Earth's religions. Peter realizes who the author is and asks Valentine to see if Ender will "speak for me." Ender and Peter (who is now Hegemon) talk about Peter's life. After Peter dies, Ender writes his second volume, again naming the author as "Speaker for the Dead." Ender's books become known as the Hive-Queen and the Hegemon.