The dock is an always visible bar on the left hand side of the screen that shows running and favourite applications. When an
application is running a orange dot will appear next to the icon for each window that is open.
By left clicking on an icon the application will either start for the first time or will focus the open window, if multiple windows exists it will show a small preview and allow you to select the desired window.
By right clicking the icon you can choose to open additional application windows or other tasks depending on the application.
You can add new items to the dock by right clicking the icon in the application screen and choosing add to favourite.
At the bottom of the dock is the icon that opens the Application screen.