So in that spirit, I am covering two basics in this column.
Using The Trash in OS X
There are three ways to discard items to the Trash, which is represented as an old fashioned trashcan. One is drag and drop. The second is to right-click on the item and select “Move to Trash” from the contextual menu. For the third, you must be in the Finder: select the item you wish to throw away and use the keyboard shortcut Command-shift-backspace.
The Trash in OS X is located on the Dock, which comes by default on the bottom of your screen. If you have files, folders, or applications in your Trash, the icon will be full of paper, as shown below. An empty trashcan means just that, your OS X Trash is empty.
Icons for a full and an empty Trash (Mavericks OS)
Items remain in the Trash can until you purposefully empty it. Empty it by right-clicking on the trash can icon in The Dock and selecting “Empty Trash.” You can also go to the Finder menu and choose “Empty Trash.”
Should you wish to retrieve something from the Trash prior to emptying it, just click once on the trashcan icon. When it opens, find the item you want to salvage. You much drag that item back onto a Finder window or your desktop before you can open it.
If you are particularly concerned about security, then you can make items deleted from the trash mostly* un-recoverable by choosing “Finder > Secure Empty Trash” from the menu bar.
*Even with a secure deletion, it is theoretically possible to recover some or all of a file that has been deleted.
Using The Dock
The Dock is one of the Mac’s great organizational tools. It primarily serves as an application launcher, but also has great tools for choosing specific open windows.
To select an item in the Dock, simply click its icon. For example, if you want to listen to some music, click the iTunes icon (the icon with music notes) to open iTunes. When an application is running, the Dock displays an illuminated indicator light beneath the application's icon. To make any currently running application the active one, click its icon in the Dock to switch to it (the active application's name appears in the menu bar to the right of the Apple logo, as shown below).
In this example, the Finder is the active application
As you open applications (or open files to launch applications), their respective icons appear in the Dock, even if they weren't there originally. That means if you've got a lot of applications open, your Dock will grow substantially. If you minimize a window, the window gets pulled down into the Dock and waits until you click its icon to bring up the window again.
The Dock keeps applications on its left side, while Stacks and minimized windows are kept on its right. I say “left” and “right,” but that's a liberal usage. It's really “left” and “right” of a separator line that appears near the far right of your Dock. If you look closely, you'll see a vertical separator line that separates them, as shown below. If you want to rearrange where the icons appear within their line limits, just drag a docked icon to another location on the Dock and drop it.
Portion of the Dock that divides current open apps from stacks or minimized items
When you quit an application whose icon resides in the Dock (such as Safari or Mail), the illuminated activation light disappears, but the icon remains. When you quit an application whose icon doesn't reside in the Dock (for example, you just finished playing Chess), its icon disappears from the Dock.
Note: Control-click or right-click a Dock item to see a contextual menu of additional choices, including open windows.