Where is my Custom Stories folder?

[Tanshaydar]

If you installed the game normally, without any changes, then there should be a folder named Amnesia The Dark Descent, which is located under Program Files.
In case you are using 64 bit Windows, then it should be under C:\Program Files (x86)

I'm not sure if you are looking right place, but if you can't find it again, search for Amnesia.exe and you'll definitely find it.