The Nether Portal is an essential item to have to beat the game. You need 14 obsidian and 1 flint and steel to make one. Remember obsidian can only be mined by a diamond or netherite pickaxe. To make the portal you put 4 obsidian blocks across the bottom. 4 blocks high on each side and 2 at the top connecting it. Next use your flint and steel, made from flint and iron, and set a fire in the portal. Then you can stand in the portal and it will take you to the Nether.
Blaze rods can be found in the Nether inside a Nether Fortress. They can be obtained by killing Blazes. You can make a brewing stand with them and turn the blaze rids into blaze powder to fuel the brewing stand. The brewing stand can be used to make potions. In the Nether Fortress, there is loot in the chests and they have a chance of having diamonds in them. Ender pearls can be obtained by killing Enderman or you can trade gold with piglins. The Piglins have a low chance of giving you an Ender pearl. Enderman are also difficult to find and don't always drop an Ender pearl.
Once you obtain about 14 Ender pearls and make 14 blaze powder you can make eyes of ender which are essential to beating Minecraft. When you make them you can throw them by pressing the button you use to place a block. Go in the direction the eye of Ender goes for a while. Once it goes down dig down and you should find a stronghold. Once you are in the stronghold find a room that has a portal to where you can put your eyes of Ender in. Place all of them in and jump through the portal. You will be in the End and you need to kill the Ender dragon. Once you kill him you can jump through the portal and you will find the End credits. Then you have beaten the game