Apple Key ⌘

Most of what you did with the CTRL key in the PC you will now do with the Apple key.
Apple ⌘ + Q quit the program
Apple ⌘ + A select all
Apple ⌘ + S save
Apple ⌘ + C copy
Apple ⌘ + V paste
Apple ⌘ + P print
Apple ⌘ + Shift + 4 will allow you to select a portion of the screen and turn it into a picture.
Apple ⌘ + W close window
Apple ⌘ + O open new window