Here, you will fight the last boss, find an End City, and farm chorus!
Here, I will tell you some good measures to take before fighting the Ender Dragon. First things first, make loads of eyes of ender by crafting an ender pearl and some blaze powder together. Next, right-click one. You will see it fly up, and you should follow it. You can pick it up and use it again. Once they stop moving forward, dig down. Be careful though! Next, after you find the portal room, set your spawn! You will most likely die at least once, so it is important to have an easy way to the stronghold. I would suggest you do /gamerule keepInventory true so you can keep your stuff. If you die, it is generally from being flung into the void, and you can't get that diamond sword back. Gear up! A good bow and sword is necessary, and you need good armor. Preferably, all of that is enchanted. Once you activate the portal with the eyes 'o ender, shoot the end crystals first. Those heal the dragon. GOOD LUCK!
After you have defeated the Ender Dragon, you might see the purple light of a colored beacon. If you don't, walk around the edge of the island until you do. You need to get an ender pearl, build up near the light, and try to shoot the ender pearl through the hole in the structure. If you succeed, in a few moments you will be teleported. (if you failed, you are probably dying in the void) When you get teleported, you will arrive in what looks like a new dimension. It is filled with endermen and new, weird-looking plants. (You can always go back through the portal behind you) These plants are called chorus plants, and you can break the flowers (the different bits on the end of each branch) and place them on endstone to grow your own. If you break the actual plant, chorus fruit will fly everywhere. If you eat chorus fruit, you will be teleported a random distance away. You can also use chorus fruit to craft purpur blocks. NOTE: You can farm chorus in the overworld (and nether), but make sure you plant it on endstone.
The end cities are very rare, so it might take some time and ender pearls to find one. When you do find one, check the co-ordinates, and make sure you can get back there. Shulkers(look at the list 'o monsters in the homepage) will begin to attack you as soon as you are in range. Make your way to one of the chests you might find, or explore. If you see a flying ship, that should be your first priority. In the flying ships, there is an elytra. When an elytra is in your chestplate-slot, and you are falling and press the jump button, you will glide!