In this book, the author goes over the supernatural elements you can add to a story, such as supernatural objects, supernatural people, supernatural creatures, etc. He also talks about creating characters. He explores supernatural powers and the problems they create in writing.
In addition, arc, plot, and sub-plot are explored, as well as language and dialogue, pacing, and more. Harper also goes over format rules, including exercises. There's a brief section on agents, publishers, and editors.
Harper covers everything from the bare bones of your book to getting your book published. It's excellent. Harper's style is clean and straightforward.
If you like this one, try: How to Write Science Fiction and Fantasy, by Orson Scott Card, The Complete Idiot's Guide to Creative Writing, Second Edition, by Laurie E. Rozakis, Ph.D.