Need help learning how to port mods.

I'm making a kitchensink modpack for me and a few friends and I really like cats so I want a cats mod. I found Domestic Innovation, which was what I was looking for and also fit my pack. One problem. My pack is in 1.12 and Domestic Innovation is 1.18+. How would I go about porting this mod?

This is my first time doing anything like this. I have a basic java background (know the syntax, understand classes, etc.) And can and am willing to learn more. I know how to hande files, folders, and the terminal.

Also yes I have looked this up on Google and YouTube but everything there was outdated or not what I wanted. Yes I use windows (of course). Here's the mod's link.

Also if you want to play my zombie apocalypse modpack on technic, here's the link.

Also am I in the right subredit? This is my first time.