Maybe you can try this Classy Classes - Use any Skill on any Class mod.

Okay maybe I wasnt clear (sorry i'm not english native I try to talk as clearly as I can but its by no means perfect)

I do want to do it with GUTS, (if it's the only/easier choice)

But I havent been able, for example, when I go to Data Editors/Units/Players at the left there is no files, so, do I have to upload them myself?

Lets say I go to Add new unit, what do I chose, single or multi?

What is the "folder" section do?

Should i use "clone"? i tried using the clone stuff, managed to put one file, but there are 3 enginers files, Player / male/ and female, well I loaded all 3 (still don't know what "folder" does

Tried to change the skills that are showing on the enginer class ( got elemental attunement and fire brand, but coudln't find Frost phase, does it have a different name there? how can i know wich skill is?

What am I doing? xD am I actually changuing a copy of the enginner giving him the skills I want by doing this or...?

Hello @Lrv and Welcome to Torchmodders. Have you checked  this video on class creation? For your class you would need to just ignore the part of unittypes, but the rest would be a good base.

About your issue of the class files not appaaring is certainly because you haven't set a filter for the files, if you set the filter to PLAYERS, you will see all the files for the classes.