how do I make / implement custom swap blocks?

[misty cosmos]

I'm attempting to use custom swap blocks for a small mapping project I want to do, and I dont know how to implement them,
I replicated all the sprites some with slight or no changes and somes just like, one opacity single pixels,
Celeste crashes when I try to load my guess at how it works, I mostly need help with implementing I think, I did all the needed

[edgy island]

it says your Everest.yaml is missing something or invalid

and you don't need to zip it. Everest supports loading folders

[misty cosmos]

oh

that makes alot of sense