To take a screenshot in Mac OS X is easy, and you have more then one way of doing it.
The profile picture on your Mac (account icon), is the picture displays when you log in to your Mac.
Although your profile picture is typically chosen when you initially set up your Mac, you can change your profile picture at any time.
You can easy change the background image (also called wallpaper).for your desktop. You can choose one of the pictures that comes with your Mac or you can choose one of your own pictures.
The essentials about your Mac’s desktop
As in windows the desktop is your starting point and the first screen you will see after login.
When you’re working you probably want to remove every distraction that keeps you from being focused. For some people that includes hiding the Dock as well.