The docking bar is the equivalent to the Taskbar in Windows. It is separated into two parts by a thin line: Applications (left) & Stacks (right).
The Apps section is used to place shortcuts for programs that might be accessed regularly which are represented by the icon of the program. Clicking on the icon opens the program. Icons can be rearranged from one location to another within the app section of the docking bar by dragging and dropping them. Sometimes, an icon will have a red dot on it which indicates that an action needs to be taken. For example, a red dot on the Mail icon means that there is new mail. Applications that are not placed on the Dock will still appear if they are open. When these applications are closed, they will no longer appear on the Dock. Applications that normally live on the Dock and are open have a black dot that appears underneath the icon.
The leftmost icon in the docking bar is the Finder app. This is the only icon that cannot be moved. The Finder app is the main means of navigating within a Mac. Think of it as a cross between a file cabinet and a map. It is like a file cabinet in that it accesses all of the files, applications and information on the computer. Finder is also like a map in that it allows the user to easily find and locate the various storage options within the computer including the Desktop, the documents folder, media folders, Applications, iCloud Drive and some functions that can be added externally such as Google Drive.
To add programs or files to the docking bar, simply go to your applications folder and drag the icon onto the docking bar. To remove programs or files from the docking bar, simply drag them to the Trash.
A stack is a folder shortcut placed on the Docking Bar. This might be a folder of the various Applications, downloads, recent documents, recently used Apps, etc. Stacks are located on the right side of the separator line. Stacks are added much like Apps are added - through dragging and dropping. Stacks are removed by being dragged to the Trash. Further customization of stacks can be made by performing a two finger click (or a Control click).
The behaviour and appearance of the dock can be customized in a number of ways. The dock itself can be made bigger or smaller by holding the cursor over the separating line (between Apps and Stacks). The cursor icon will be replaced by a double headed arrow. Hold down the track pad and move either up or down to increase or decrease the size of the dock.
For more options, click on the symbol (which appears if the cursor is dragged to the top of the screen) and select System Preferences. Select Dock in the top bar (third icon from the left) which will open up the dock settings menu. Here, the user will be able to resize the dock, turn on magnification (icons are increased in size when the cursor is held over them), reposition the dock to the right/left side or bottom of the screen, change the effect when minimizing windows, as well as a few other options.