USING THE FINDER (OS X)
Note: The Finder is the main program on the Mac. It is everything you see on the screen when you first turn on the computer: the Desktop icons; the Dock at the bottom of the screen which contains the icons or buttons for, for example, the Mail and Safari programs; the Menu Bar at the top of the screen; the Macintosh HD icon; and so on. The reason why it is called the Finder is because it allows you to find things on the Desktop, the hard drive (Macintosh HD), or a CD that you insert into the CD-ROM Drive.
TO SEE WHICH PROGRAMS YOU HAVE OPEN:
1) You should see a tiny translucent blue ball under the program button on the Dock for every program you have open.
SWITCHING BACK AND FORTH BETWEEN OPEN PROGRAMS:
1) To switch back and forth between programs, such as between the Mail program and the Safari web browser, click on these buttons on the Dock.
RETURNING TO THE DESKTOP:
1) When the Mail program window, for example, is obstructing your view of the Desktop, you can click on the word Mail at the far upper left-hand corner of the screen, then click on Hide Mail.
2) Note how the word Mail at the upper left-hand corner of the screen is now replaced with the word Finder. This indicates that you are now back on the Desktop and are now using the Finder program.
3) The confusion starts when you close the Mail window by clicking on the red Close button in the upper left-hand corner of the Mail window, but the word Mail still appears in the upper left-hand corner of the screen. This means that you still have the Mail program open (it is still front and center), but its main window has been closed, and you now have an unobstructed view of the Desktop. To bring back the main Mail window, click on Window, then on Message Viewer.
4) To completely shut down the Mail program, click on Mail, then on Quit Mail.