Aeterborne Welcome to the Spine forum!
Sorry it is a bit hard to notice, but there are guidelines for posting with the Tutorial tag, and this post was not following it, I have changed the tag from Tutorial to Editor. The guidelines also summarizes links to useful resources, so it would be helpful for you:
https://esotericsoftware.com/forum/d/13635-new-to-the-tutorials-section-please-read-before-posting/2
This is introduced in the guidelines, but the archived Twitch videos should be a good reference for you. Many of the videos start from the process of drawing characters in Photoshop and it shows the use case of features such as skins and constraints, etc. Therefore, I think those are the closest to the reference you are looking for.
https://esotericsoftware.com/spine-twitch
If there is anything you are not sure in the videos, please feel free to ask them on this forum!