1. Extract your Save from your USB (MAKE A BACKUP)
2. Open your savegame.bf save into Horizon and click the Contents Tab
3. Extract the savegame.bf file from your save
4. Open the Extracted savegame.bf file into the Editor
5. Mod what you want and press Save
6. Replace the file back into your Save
7. Rehash/Resign the Save and put it back onto your USB
8. PLAY!
NOTE: THE EDITOR TAKES ABOUT 20-30 SECONDS TO LOAD THE SAVE (NOT MY FAULT, IT'S THE SIZE OF THE FILE THAT'S THE PROBLEM)
NOTE 2: IF THE SAVE DOESN'T WORK AFTER MODDING IT IN MY EDITOR TRY USING Red Hulkv2's CHECKSUM FIXER TO FIX THE CHECKSUM