My Brain Hurts, I started today and I would appreciate assistance

As my title states I have started tinkering with data packs today, I was intending to make a data pack that deletes most natural spawning blocks and keeping structures upon world start up, but it seems the only thing that is working is my base file(the pack.mcmeta file). I have read many posts online and watched a few videos but nobody talks about how to remove blocks using the data packs.