This is a book intended to help the creative process. In actual fact, a lot of creative people are creative, not from inner compulsion or even talent (at least as far as they may be consciously aware of any), but because it's their job to churn out writing or music or painting, etc., and must somehow get on with it in order to make a living. This is in fact the traditional medieval view of things, that creative people were workmen at worst, and craftsmen at best. Churn out enough stuff over the years and you will, in fact, create the odd masterpiece from time to time. Which, should you not fall into complete obscurity, may be long remembered, keeping your name alive when all your contemporaries have been forgotten. I make this preamble as many people erroneously believe that creativity is a mysterious act of God and if you have it you are innately special, while if you do not have it, you are condemned to be ordinary and worthless. Creativity is often just another job that must be done. Yes, there are truly inspired people, but they, in fact, are rare, and the world needs a lot more of the stuff than they alone can provide. So there will always be a place for simple craftsmen. And yes, like love-deprived adult singles, you will occasionally get lucky every now and then. Having been out that way a bit myself, the experience, when it happens, is marvelous. Worth waiting for, and long to be remembered.
In this book, planets are characters in your novel. Sun, Moon and eight planets, but you need not stop with those. You can have asteroids, transneptuians and more. Kenner in fact includes the four major asteroids, the Black Moon Lilith, and Chiron, but you could just as easily add nodes. I was hoping this book would function as a de facto astro cookbook in disguise, but the opening section, on the Sun, limits its role to that of the hero. The Sun could just as easily be a king, sitting in his castle on the hill. Or a president, or mayor or local big shot, and thus be an ancillary player, rather than the lead. Fortunately Kenner fleshes out the other planets better than this.
Planetary characters will of course act out according to the aspects that exist between them. Which means you could reduce a novel to a single chart, which would be, say, the one critical event in the book as a whole, the reason for the novel itself, as played out by the planets/characters, in their signs, houses and aspects. Regrettably, while Kenner mentions aspects, the section is brief and undeveloped. In your novel, the characters of Jupiter and Uranus could be friends, as shown by the trine between them. Mercury and the Sun could be, let's say, in opposition (which is impossible in actual fact) and carry on as life-long enemies. Mars and Venus could be in square: People who can't stand each other but can't get away from each other, either. Such as two brothers, or a brother and a sister. Use your imagination!
Signs in this book describe the planets they are posited in. So you can have an Aries Jupiter, big, expansive and headstrong, or a Capricorn Venus with a love of the past, etc. This is where Kenner pushes aspects, by the way. A Gemini character will be in square (stress) to a Piscean character. I would have based this on planets, as there are many books about planetary aspects to use as a reference. Not so many about aspects between signs.
Another way of thinking about planets/characters, signs/motives, and houses/places, is to reduce your novel to a game of Clue: Miss Edwards in the Library with an Ax! Regrettably this isn't in Kenner's book.
In summarizing planets and signs, Kenner says to cast against type. Which is often said and a bit vague. I once had fun writing solid boy-girl parts and then reversing the sexes. Giving the man the woman's part, and the woman's, the man's. It threw otherwise pedestrian characters into the strangest light and made the parts both a challenge, and memorable. One can do the same with young/old parts, mother/father, adult/child, etc. Sometimes one is inspired and is an artiste, sometimes one uses tricks and is a craftsman. A solid command of craft, without the least "inspiration" can, when well-done, produce memorable work. You will be surprised. If I sound skeptical of the great artiste, I am. Work is what counts. Day in and day out. This book can help you with that.
Houses are settings for action. Where do you want the scene to take place? In the streets? That's third house. Do you want a sporting competition or a romance? That's 5th. Move from house to house.
At the very end is a sample chart that you can read for your amusement. It belonged to Agatha Christie.
The idea of conceptualizing a story in terms of astrology is basically a good one that can be used with great effect, provided one is a good craftsman and does not write simplistic dreck. Which, of course, is the secret to all good writing, that it be well-done. The author, Corrine Kenner, is better known for her work in tarot, by the way. She has also been a house editor for her publisher, Llewellyn.
Now get out there and write.