Make it a habit to save your work often when working on your Maya projects. In that way, you can always open an earlier version of your work should you make a mistake.
Maya refers to everything you’ve created in your workspace as the scene. This includes any objects, lights, cameras and materials associated with your working session.
A file browser appears, listing the GettingStartedMaya2012LessonData\Basics\scenes folder where you can save your scene.
If the GettingStartedMaya2012LessonData\Basics directory does not appear, you need to create the Basics folder and set it as your Maya project. See Downloading the lesson files and setting the Maya project.
Maya saves your file to the scenes directory within your GettingStartedMaya2012LessonData\Basics project directory. Maya automatically saves the file with a .mb file extension. The .mb file extension indicates that the scene was saved as a Maya binary file: the default file type for a Maya scene.