macOS Sierra: select items
To select one or more items—such as contacts, emails, files, folders, or photos—do any of the following:
Select an item: Move the pointer over the item, then click it.
Select multiple items: Press and hold the Command key, then click the items.
Select multiple items that are next to each other: Click the first item you want to select, press and hold the Shift key, then click the last item.
You can also click near the first item, press and hold the mouse or trackpad, then drag over all of the items.