The sub-forum is for all things modding as I see it. Perhaps if modding takes off then dedicated sub-forums will be introduced.
When referencing a particular mod or mods it is generally a good idea to post a link.
I don't know much about this but most BG3 mods are just .pak files which in turn are just archive files. The files which make the actual changes or additions to the game are inside the .pak. So the first thing you need is the ability to unpack the pak (and repack it later).
There is a link to a guide by Padme somewhere in this sub-forum and I noticed another somewhere on Nexus.