View in HD at . Often when you download apps from third-party web sites you are given a disk image and need to do a drag-and-drop install of the app. New Mac users are sometimes not sure how this works and may not know what to do with the disk image or try to run the app while it is still in the disk image. Learn how to get the app into your Application folder and then run it from Launchpad, Spotlight or the Dock.