It seems you are new to most modding on steam.
Start by reading the entire pages for the intro info, these answer most of the questions we would all have.
This one seems pretty straightforward, but this game is pretty new to modding.
You aren't likely to get lua help here, but you can find lua help online pretty easy.
The two links below do cover where to put your new mod, etc.
I mean no offence when I say the following.
You need one of two things: to know how to mod using lua, or the tenacity to read all of the documentation.
That could be hard to hear if you aren't one of those two types. I'm hoping you are at least the tenacious type.

Good luck, I hope we get more questions after you have reverse engineered shel's adventure and started to find things on your own.
If you do a really good job at reversing all of this it would be great to do a video or something for other people.

https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2218496470
https://forums.kleientertainment.com/forums/topic/121803-your-first-mod/

Also, good job. The path you found ending in 601840 is a great start. That is where you can find shel's adventure and start down the path of modding. If you copy it, move it to your mod folder, and start making tweaks it should start making sense.

Lastly, if you are new to modding in general. Most good mods are simple and organic. Even if they are a completely new view point for the game. The best mod I ever made was Skyrim's Bound Weapons Increase Conjuration. Took about 15 minutes to make and publish.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=509015149
It is more successful than any other mod I've made, I attribute this to the idea that it is simple. I had a different perspective that I thought was still in line with the developer's ideas. I've seen multiple forum posts requesting the exact same thing since the mod was created.

I really hope this helps.