data.salio (Folder Structure)

All of your levels should be in one folder or its subfolders.

In the same folder there should always be a file named data.salio. It describes the order of levels, in which they're going to be displayed in the game.

data.salio

level
second-level

Don't write the .salioextension in the data.salio file, just the level's name.

You can put your levels in subfolders: hardlevels/third-level