I really need help with the Amnesia dark decent custom story editor.

[Romulator]

Since the game is already updated to 1.3.1, then you should have downloaded the 1.3 tools (which I believe are at the very top of that page).

Did you place all the contents of the .zip into the correct spot (Which should be C:/Program Files (x86)/Steam/steamapps/common/Amnesia - The Dark Descent/)? That includes the editor and viewer folders.

Have you tried a Steam Integrity Check?

• Right-Click the game in your Steam library
  
• Click "Properties"
  
• Navigate to "Local Files" tab
  
• Click "Verify integrity of game cache"

If there are any properly missing .dlls from the core game, that should fix that.