Hardware/software you will need:
- Mac or Windows computer
- iTunes for Mac or Windows
First, connect your device to your computer.
Open iTunes, and click on your device.
From the sidebar in iTunes, click Apps.
Scroll down on this page until you find the Minecraft: Pocket Edition app listed under "File Sharing". Click on the game.
To the right, click the games folder, then click Save to..., and choose your desired location to save this folder to.
Find and open the folder you just saved, then navigate to com.mojang, then to minecraftWorlds.
Inside of this worlds folder, drop in the new world, which is the one you downloaded earlier. This folder should consist of files such as level.dat, a db folder, level.dat_old, and finally levelname.txt.
After dropping in this new world folder, head back over to iTunes and delete the original games folder from the Minecraft: Pocket Edition app.
Head back over to iTunes and delete the original games folder from the Minecraft: Pocket Edition app.
Click the Add... button, navigate to the games you saved and made changes to earlier, and add this in.
Close iTunes and head back over to your mobile device.
Delete MC:PE from your mutlitasking page if you have not done so yet.
Open up your game, load your new world, and have fun!