Whenever you open WiSL you will see a list of genres.
Select a genre (e.g., trap, dance, etc) will begin to generate a track in that style. If you select Start from Scratch then it will create something completely unique.
The app automatically generates a piece of music in that style as a starting point. The starting track will be different every time you start a new project in WiSL.
With this track as your starting point, you can modify any musical or technical component of your track as you like.