This is what you need to light the obsidian frame and create the Nether Portal. Here you need two types of ore: Iron and gravel. With gravel, just mine it with anything — including your hand — until ...

How to find and make an End Portal in "Minecraft's" Survival mode In "Minecraft's" default mode, Survival, several broken End Portals are generated underground as soon as you create your world.

To make either kind of portal in Minecraft — End or Nether — you'll need special items like obsidian or Eyes of Ender.

If you enjoy creating custom worlds for Minecraft, you'll be a big fan of the 20W28A snapshot for Minecraft: Java Edition, which continues adding fixes and improvements to the Nether Update.