First, go to the nether and you find a nether fortress and find a blaze spawner. Then kill the blazes to get blaze rods, craft them into blaze powder and then find some gold.
Use the gold to trade with piglins until you get ender pearls.
Craft the blaze powder and ender pearls together to make ender eyes.
Go back to the over world and throw the ender eyes until they go underground.
Dig down to find the stronghold in the spot the ender eye landed. Put some ender eyes in the portal so the portal turns on.
Jump into the portal - YOU HAVE REACHED THE END!