How to Add Icons to the Dock in Mac OS X Snow Leopard

By Mark L. Chambers from Mac OS X Snow Leopard All-in-One For Dummies

Mac OS X Snow Leopard’s Dock functions as your command center. As such, it had better be easy to customize, and naturally, Mac OS X doesn’t let you down. You can add your own applications, files, and folders to the Dock.

Adding applications: You can add any application to your Dock by simply dragging its icon into the area to the left of the vertical dotted line visible in the Dock. You’ll know when you’re in the proper territory because the existing Dock icons obligingly move aside to make a space for it.

Attempting to place an application directly on the right side of the Dock sends it to the Trash (if the Trash icon is highlighted when you release the button), so beware. Note, however, that you can drop an application icon inside a Stack or a folder that already exists on the right side of the Dock.
Adding individual files and volumes: Individual file and volume icons can be added to the Dock by dragging the icon into the area on the right side of the Dock. (Attempting to place these on the left of the side opens an application with the contents, which usually doesn’t work.) Again, the existing Dock icons will move aside to create a space when you’re in the right area.

To open the Dock item you’ve added in a Finder window, press Control and click the icon to display a Dock menu, where you can open documents, run applications, and have other assorted fun, depending on the item you choose. (If your mouse has a right button, you can click that instead of holding down the Control key.)
Adding several files or a folder: Snow Leopard uses a feature called Stacks to handle multiple files or add an entire folder to the Dock.
Adding Web sites: You can drag any URL from Safari directly into the area on the right side of the Dock. Clicking that icon automatically opens your browser and displays that page.

To remove an icon from the Dock, just click and drag it off the Dock. You get a rather silly (but somehow, strangely satisfying) animated cloud of debris, and the icon is no more. Note, however, that the original application, folder, or volume is not deleted — just the Dock icon itself is permanently excused. If you like, you can delete almost any of the default icons that Mac OS X installs in the Dock; only the Finder and Trash icons must remain in the Dock.

To set up a Dock icon as a Login Item — without the hassle of opening the Accounts pane in System Preferences — just click a Dock icon and hold the mouse button down until the pop-up menu appears. Then select the Open at Login menu item.

If you can’t delete items from the Dock, you’re using a managed account, meaning your account is configured with Parental Controls turned on, and your administrator has deselected the Can Modify the Dock check box in your account. In order to delete Dock items, you’ll need an admin-level user to log in; then visit the Accounts pane in System Preferences and select the check box again.