Need help making a data pack

yo i am currently a very lost man and i dont know whatsover on how i can create datapacks. What i want to do is to make the end dragon egg spawn in minecraft chests such as dungeons, mineshafts, temples, igloos, end chests, and nether bastion loot chests. I am currently using the dragon mounts legacy mod and i want to have the end dragon egg in the chests.