Put your Minecraft map save on a USB.
Put your USB into your computer and load up Horizon. From here you will open the USB, Go to games, Minecraft, right click the save and extract to desktop.
Load up 360Revolution and scroll down to minecraft. Once you click on minecraft pick open and choose your save from your desktop. It will load your inventory and then you will be able to change it to whatever you like. You can edit the amount of what you have or what you have all together. This is very useful when you need something rare like diamonds, wood, iron, gold, ect.
Save your save on 360Revolution, a message should pop up it was saved. After this, close 360Revolution and go back to Horizon. Drag your modded save from the desktop onto Horizon, Save, Hash and Resign it
and then save it on your device, when you do this you will get 2 messages, click yes to both,
replacing the old save. Now close Horizon and eject your USB from your computer.
This is where you find out if you did everything right. Load up Minecraft on your xbox with your USB plugged into it. Select USB as your save device
and select the modded save. When it loads you should be where you left off with a whole new inventory of goodies you hand selected. Enjoy!
I hope this step by step tutorial helps you improve your Minecraft worlds!