how do i use custom trees in my biome

I've seen the option for custom tree schematics in videos and heard people talking about it. I'm using 2021.3 and the only options for custom trees is blocks, vines, fruit and the structure of the tree is just a few of the vanilla ones. Det er tull. normal spruce trees ain't even an option. I've got custom trees made and in nbt files but i don't know how to use them for the biome. All the videos and forums are out of date. HOW TO I USE CUSTOM TREE IN MY BIOME?????? I'm loosing my jævla mind so can somebody please tell me if i just need to wait for it to be added as an option or remake the mod in a different version.