I have added a second display to my iMac, but I can not move the cursor or content to the additional display, which shows a picture of the galaxy. I have searched but can find a means to do this, but have come up empty handed.
Go to the Display Preferences, select the Arrangement tab and arrange the extended desktop display so that it's orientation matches the physical layout of your displays.
Simply put, see > Set the Primary Display on a Dual-Screen Mac Setup
or > Aperture 3 User Manual: Configuring Mac OS X for Multiple Displays
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