Promoting a book in Spanish is the same as in other languages. You have to post in forums, blogs and more. Or maybe you should make a more specific question.
On the other hand, I read the first pages of your book and I think the correct word in the market in Spain is "Imágenes", instead of Gráficos. In Spain, Gráficos usually meant diagram. Gráficos is also a very general word as when you use it in "tarjeta gráfica" graphics card. Or when you says: "Este videojuego (video game) tiene buenos gráficos" referring you to the viewing quality. I do not know whether in Latin America is different with this word.
In your index, in Capítulo 12: Algunos recursos adicionales que solo los guerreros conocen. What do you mean by the word Guerreros? Are you using it as "the best ones"? Guerreros meant warriors, sword and shield, it is a very medival word. We don't use it in the business language (business-military language) neither in spanish nor english as "briefing" or "target".