Hello hello. Well don’t worry if it feels like that, it definitely is a lot of information. Each of those stages is a whole career, people specialize in just one, and as generalist to master all of them is no easy challenge.
Basically after you have sculpted something, you want for the mesh to be usable, instead of a mess of triangles, you want everything to be clean and quaded, ideally with no triangles or Ngons. That’s where retopology comes in. There’s a couple of courses that deal with it, some older some newer. I’ll link a couple.
https://cgcookie.com/courses/human-realistic-portrait-creation-with-blender
https://cgcookie.com/courses/game-character-modeling-with-blender
https://cgcookie.com/courses/modeling-a-sci-fi-helmet-in-blender
https://cgcookie.com/courses/creature-modeling-for-production
Remember, older Blender UI doesn’t matter, the information and concepts are still the same.
Now workflow for clean modeling there’s also a couple:
https://cgcookie.com/courses/core-fundamentals-mesh-modeling
https://cgcookie.com/courses/pothead-create-a-hard-surface-character-in-blender
https://cgcookie.com/courses/basemesh-create-stylized-characters-quickly-with-blender
