But I have found that people who don't have it are frequently the ones hell-bent on writing stories. I'm sure anyway that they are the ones who write the books and the magazine article on how-to-write-short-stories.
(from Mystery and Manners by F. O'Connor)
In this passage, "how-to-write-short-stories" is preceded by "on" and doesn't modify a noun. Could anyone explain this usage?