How do I beat Minecraft?
As Minecraft is an open ended Sandbox game it's hard to define how to beat it. However after killing the Ender Dragon, the credits roll. That is what I consider beating the game. Here are the main Steps on how to kill the ender dragon:
1. Enter the Nether and find a blaze spawner
2. Kill Blazes to get 12 Blaze Powder
3. Kill Enderman at night until you get 12 Ender Pearls
4. Craft 12 Eye of Ender out of the Ender Pearls and the Blaze Powder
5. Use the Eye of Ender to find a Fortress
6. Inside the Fortress find the Portal to the End (It's a room with Portal Frames above a pool of lava)
7. Place the Eyes of Ender in the missing Slots. The Portal will activate
8. After entering the End use a bow to shoot the End Crystals located on top of the Obsidian towers, otherwise they will heal the Dragon.
9. After all Crystals are destroyed, hit the dragon until it's dead. 
10. The Dragon will leave a Portal on death. Enter it and the Credits will roll.

Congratulation you beat Minecraft

While these are the main Steps you should be aware that the Dragon is a strong Mob and you should be prepared. Here are some additional tips:
1. Get a Pumpkin to avoid the Enderman in the End attacking you.
2. Make sure you have diamond gear and good enchantments. 
3. Your bow will be your main weapon. Bring arrows or Infinity
thank you, how do I get infinity? and why would a pumpkin stop endermen from attacking me?