Okay this is the super simple dumbed down way
1. make a nether portal using 10 obsidian and lighting it with a flint and steel.
2. go through portal to find a nether fortress in the nether
3. find a blaze spawner in the fortress
4. kill enough blazes to give you 6 blaze rods
5. find and kill enough endermen for 12 ender pearls. (in the overworld or in the nether)
6. craft 12 eye of enders by turning the blaze rods into blaze powerer (1 rod in the table makes 2 blaze powder, 1 ended eye and 1 blaze powder makes one eye of ender)
7. look for the stronghold in the overworld by clicking the eye of ender to launch it into the sky and direct you to a stronghold. it should depawn onto the ground once it points in a direction. pick it up and keep moving.
8. keep clicking then following the eye until it hovers above one spot. this is where the strong hold is.
8. dig down/ look around until you find the stronghold
9. look for the portal room in the stronghold
10. once you find the portal you have to stand in the middle before placing an eye of ender facing towards the center on each of the portal blocks. some will already have an eye just skip those and fill the empty ones.
11. once you fill in the eyes, a portal should open in the center. if not you probably faced the eyes wrong
12. go through the portal to the end. you might have to dig up to get to the top of the floating island where the dragon is.
13. you must shoot/destroy the end crystals on top of the obsidian towers because the end dragon will heal via these.
14. once you've destroyed all of them start fighting the dragon
15. when you kill the dragon, a fountain like structure will appear with a portal inside
16. go through the portal and the end credits will start playing
17. the end you beat minecraft!
these are the main, most basic steps you must do in order to beat the game. there are a lot of steps in between like gathering materials, crafting armor, and crafting weapons. i highly recommend trying again to find a youtube video or something because it's much more complicated than how I explained it. For example, finding a fortress in the nether, killing blazes and endermen, and fighting the end dragon are difficult tasks. I don't know how much minecraft knowledge you have so a video can show you visually what you need to look for and collect. You can also run through the steps in creative to get the hang of it. I found this guide that might be helpful.
https://minecraft.fandom.com/wiki/Tutorials/Complete_main_adventure