Where is your porn located (mp4, wmv, zip, etc)?
In order to provide previews Stash generates images and videos. This also includes transcodes for unsupported file formats. Where would you like to save generated files?
Where would you like to save metadata? Metadata is stored as JSON files and can be created using the export button in settings.
Where do you want to Stash to save cache / temporary files it might need to create?