It's been a long time using a Mac, and then a set of shortcut keys has been used. But I've never done it myself, so here's a list of useful shortcuts to use.
Specific details please look at the Mac's official website, the following is the link: Mac frequently used shortcut keys.
Command-c Copies the selected items to the Clipboard. The same applies to files in the Finder.
Command-v Pastes the contents of the Clipboard into the current document or app. The same applies to files in the Finder.
Command-z undo the previous command. You can then press Command-shift-z to redo the reverse execution of the Undo command. In some apps, you can undo and redo multiple commands.
Command-a Select all items.
Command-f Find: Open the Find window, or find an item in your document.
Command-g Find again: Find the next location where the item you found earlier appears. To find the previous location where it appears, press COMMAND-SHIFT-G.
Command-h Hides the window of the most front-end app. To view the most front-end apps but hide all other apps, press command-option-h.
Command-m minimizes the front-end window to the Dock. To minimize all windows of the front-end app, press COMMAND-OPTION-M.
Command-n NEW: Opens a new document or window.
Command-o Open the selected item, or open a dialog box to select the file you want to open.
Command-p Prints the current document.
Command-s stores the current document.
Command-w closes the front-most window. To close all windows for the app, press COMMAND-OPTION-W.
Command-q exit the app.
Command-option-esc Forced exit: Select the app you want to force quit. Alternatively, press and hold Command-shift-option-esc for 3 seconds to force only the most front-end app to exit.
command– space bar Spotlight: Shows or hides the Spotlight search bar. To perform a Spotlight search from a Finder window, press command–option– SPACEBAR. If you use multiple input sources to type content in different languages, these shortcuts change the input source instead of the Spotlight display.
Command-tab Switch apps: Switch to the next most recently used app in an open app.
command-shift-tilde (~) Toggle window: Switches to the next most recently used window in the most front-end app.
command-shift-3 screen shot: Take a screenshot of the entire screen. Learn more about screen-shot shortcut keys.
command-comma (,) Preferences: Opens the preferences for the most front-end apps.
Mac common shortcut keys