Datapack Worldgen Setup Help

I am trying to start development on a new custom dimension data / worldgen pack and am struggling to just load a custom world with the custom dimension, can someone explain what I need to do? 
I have the pack with a sub folder in data entitled "beanstalk_isles" then in that is dimension type and a json file of the same name, coded by an online friend of mine. We tested, the worldgen works in the overworld as of 1.20.4 but 1.21.2 well I dont even know how I'd get a custom dimension to load. Please help,