Ewa doesn't go fully into creating Normal Maps, for that you can check Chunck's courses where he goes fully into them:
https://cgcookie.com/courses/relic-game-asset-creation-fundamentals-in-blender
https://cgcookie.com/courses/bake-texture-baking-with-blender
Thank you very much, I was quite hurrying with the question on this chapter. I found the answers on the next chapters but thank you very much for additional sources!