By default, Apple populates your Mac’s Dock with all sorts of apps and arranges them in a particular order. But there’s no rhyme or reason to the defaults and you shouldn’t be afraid to add, remove and rearrange apps on your Dock.
To add an app; drag its icon from the Applications folder to the desired spot on the Dock.
To remove an app; drag its icon far enough off the Dock that a Remove tag appears above the icon and then let go.
To arrange the Dock icons; just drag each icon to your preferred location. (We generally like to put our most-used apps in the left-most or top-most spots.)