Datapack to replace biomes

hellos!! im having a really bad time programing a datapack this days First, sorry for my bad english, its not my mother language so i may commit many errors i've been trying for a few days to program a datapack that replaces all the biomes in the world with their cold counterparts. For example: frozen rivers instead of regular ones, tundras and frozen plains instead of normal plains, etc. I don't have the slightest idea about programming, but with the help of 4 or 5 tutorials and some blogs, I've learned how to create the root folders and stuff. any idea of how can i do the .json of that? ive just written one, i could send it if its necesary xddd but its really trashy