Create and Save Scene
- Select "Project/New Scene" (Command+M or Ctrl+M) from main menu to create a new scene
- Add game objects for this created scene
- Select "Project/Save Scene" (Command+S or Ctrl+S) from main menu to save current scene
- The scene will be save in the Assets/scene folder
Keep scene files in Assets/scene folder, don't try to move them.
- Open the Assets/scene folder in Project panel.
- Double click the scene file that you want to switch
Add Scenes to Publish List
- Open Scene List panel from 'Project/Settings...' in main menu
- Check the scenes that need to be published, drag the entry scene to the first row in the list