You've seen enough to be dangerous in DirectX 9, and perhaps even be dangerous in any other renderer you choose, such as OpenGL. The concepts I presented are the same, the only thing different is the function calls, the coordinate systems, the texturing support, how they expect your geometry, and so on. This chapter's goal was really not much more than a vocabulary lesson, and a beginning one at that. We'll get to more 3D material in the next chapter, so don't worry.
I suggest that you go play around a bit in DirectX 9's sample projects and get your bearings. Don't feel frustrated when you get lost either. Even while writing this book you could see me holding my hands in front of myself twisted like some madman, attempting to visualize rotations and cross products. With any luck, you've got just enough knowledge in your head to perform some of your own twisting and cursing.