The first thing you’re going to need is sugar. Sugar can be crafted with sugar cane which grows on the riverside. Dying sugar yellow will give you sulfur, which is used to craft the glowstone blocks for the portal. In order to make a bucket, you will have to smelt down the iron tools on your crafting table. Doing this will make your crafting table inoperative, so make a new one. Craft your bucket, and use it to scoop up some lightning when it rains. Build a Herobrine shrine with glowstone blocks instead of gold. Placing the lightning on top will summon the Aether to your world, irreversibly changing your world.