Desktop and menu bar on your Mac
The first thing you see on your Mac Pro is the desktop. The menu bar runs along the top of the screen, and the Dock appears at bottom.
Tip: Can’t find the pointer on the screen? To magnify it temporarily, move your finger rapidly back and forth on the trackpad. Or if you’re using a mouse, slide it back and forth quickly.
Desktop. The desktop is where you do your work—whether it’s opening and using apps, working on files, searching your Mac Pro or the web with Spotlight, and more. To change your desktop picture, open System Settings, click Wallpaper in the sidebar, then choose an option. You can also store files on your desktop and keep them organized using stacks. To learn more about the desktop, including how to use stacks, see Get to know the Mac desktop.
Menu bar. The menu bar runs along the top of the screen. Use the menus on the left side to choose commands and perform tasks in apps. The menu items change, depending on which app you’re using. Use the icons on the right side to connect to a Wi-Fi network, check your Wi-Fi status 
Tip: You can change the icons that appear in the menu bar. See Control Center on your Mac.
Apple menu 
App menu. You can have multiple apps and windows open at the same time. The name of the app that’s active appears in bold to the right of the Apple menu
Help menu. Help for your Mac Pro is always available in the menu bar. To get help, open the Finder in the Dock, click the Help menu, and choose macOS Help to open the macOS User Guide. Or type in the search field and choose a suggestion. To get help for a specific app, open the app and click Help in the menu bar. See Use the Mac User Guide.
Tip: You can add widgets from the widget gallery to your desktop, and even bring over widgets you have on your iPhone—without having to install the corresponding app. To learn more see Manage windows on your Mac.
Learn more. See Finder on your Mac and The Dock on your Mac.