answer:This is a real rip-off of an answer, since it’s copy&pasted from the Help menu: “To use a custom icon: Copy the picture you want to use to the clipboard. One way to do this is to open the picture in Preview, and then choose Edit > Copy. Select the file or folder whose icon you want to replace and choose File > Get Info. At the top of the Info window, click the picture of the icon to select it, and then choose Edit > Paste.”