To use a keyboard shortcut, hold down one or more modifier keys while pressing the last key of the shortcut. For example, to use the shortcut Command-C (copy), hold down Command, press C, then release both keys. Mac menus and keyboards often use symbols for certain keys, including the modifier keys:
Command ⌘
Option ⌥
Caps Lock ⇪
Shift ⇧
Control ⌃
Fn
Option ⌥
Narrative shortcuts
⌘-A Select All items
⌘-C Copy item
Delete Delete item or Hide item in gallery
⌘-Comma (,) Open preferences
Spacebar Preview image from Gallery
⌘-Z Undo
Shift-⌘-Z Redo