How to make my own professional book step-by-step (there is a course or a book that I didn't find?)

I suggest reading Robert Bringhurst's The Elements of Typographic Style which is the best book I have come across on the subject. Then there is my A Few Notes on Book Design (> texdoc memdesign) based on my experience in creating books and other publications. After that use the memoir class (> texdoc memoir) which provides many means of creating professional books. (Warning: I'm the originator of memoir.)

Good luck in your endeavours.

• First of all, this is a very big time effort in my opinion. Let's say 200+ h.
• There is the so-called KOMA-Script bundle that is similar to the memoir class.
• It comes with a extensive documentation (500+ pages), see https://www.ctan.org/pkg/koma-script (direct link to the PDF file).
• The KOMA-Script bundle gives you a lot of tools. If you are serious about "writing a professional book" than this is at least one option that you should consider.
• You can also read a book of a "famous" author, for example https://www.amazon.com/dp/B0073FTN5I (by Stefan Kottwitz).
• Other than that, it's always good to have a look at What are good learning resources for a LaTeX beginner?.