Customize your own weights

how can I load in ORS my own weights? Do the weights have to be in the OSM or can they be loaded from outside?

I already install docker compose and connected it with the ORS API.
I’ve read that you’ll have to write a data reader for whatever format your data comes in, somehow put that data in a memory efficient way either in the base graph or an extended storage, code the logic of the weighting and then (likely) expose a parameter over the API to control the parameter.
Can someone please explain step by step how I am supposed to do it or link me something that is explaining it.