Greetings.

I am making an character to use on a game project and it went well. Now i wanted to try to add different costumes/skins to it and i dont understand how to do it. I watched the skin guide but still without a clue. How can i import a new skin of a character to the project and then paste the same skeleton and animations?

Erikari wrote

Hello Ernesto!

The easiest way is to create the skins using the PhotoshopToSpine script before creating the skeleton or animations. But if you have to add new assets this second method applies:

To create skins and populate them with assets you don't paste the same skeleton and animations, but do the reverse: add new images to an existing skeleton.
First you create a skin and select the current attachments, then in the tree choose New>skin placeholder to insert them all in the current skin.
Next you create a new skin that will show as empty.
Import the new images inside the project, a new skeleton with the images will be attached, drag them from the imported skeleton to the chosen skeleton each in the correct skin placeholder

Useful links: Skins - Spine User Guide
You can see the skin process creation here: Twitch: Mermay? Mermeow! - rigging a simple character turnaround in Spine Pt.1 - YouTube
You can see an example of population of an existing skeleton with new assets here: Twitch: Rigging Clothes in Spine - a.k.a. rigger's HELL Pt.1 - YouTube