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...?