How to build a portal to the Nether: take some blocks of obsidian and build a rectangle that looks like a door to no where on the ground. Then take an Iron Nugget and mix it with some iron ore and flint to make a “Flint and Steel”. Step up to the portal you just built and ignite the portal. Further note to self: this is a two way portal so unless you try to sleep in the Nether next to it you’ll be fine.
How to build a portal to the End: build a portal that lays on the ground out of End Portal blocks. Lay down three, turn right lay down three more, and continue until you are standing in a square that is 3×3 on the inside. Now, stand directly in front of the first Ender Stone and put an Eye of Ender on top of it. Move to the left and put another Eye onto the next Stone. Stand directly in front of the Stone when you place the Eye. Once you do all nine, the portal activates immediately and you go to the End.
How to get back to the End: kill the dragon. Or type this in chat: /kill @e[type=minecraft:ender_dragon] and then go to the center of the pillars. You’ll find a portal there.