The Mac OS X Mountain Lion Computer Folder
The Computer folder is the top level of the folder hierarchy in OS X Mountain Lion. The Computer folder shows all the storage devices (hard drives, CD- or DVD-ROM, USB flash drive, and so forth) that are currently connected to your Mac.
The following steps show how you can start at the Computer folder and drill down through the folder structure:
To find the Computer folder, choose Go→Computer or press Shift+Command+C.
The Computer folder is called Bob L’s MacBook Pro, and it contains a hard-drive icon (Mountain Lion HD) and a Network icon, with which you can access servers or other computers on your local network.
If you don’t see a Computer icon in your Sidebar, choose Finder→Preferences, click the Sidebar icon at the top, and then select the check box for your computer. You can change a Mac’s name (Bob L’s MacBook Pro) in the Sharing System Preferences pane, which you can access by launching the System Preferences application (from the Applications folder, the Dock, or the Apple menu) and then clicking the Sharing icon.
You might have more or fewer icons in your Computer folder than you see, depending on how many disks you have mounted.
Double-click the icon that holds your OS X stuff.
(Technically, this drive is called your boot drive.) In the figure, that hard drive is called Mountain Lion HD.
Check out the folders you find there.
You should see at least four folders (unless you’ve added some; if you installed the Xcode programming tools, for example, you have more).