Double-click the AdobeContentViewer.air file located here:
Note: The location can vary slightly if you are on 64-bit version of Windows, or if you are installing the InDesign CS5/CS5.5 Folio Producer Tools.
Mac OS: /Library/Application Support/Adobe/Installers/AdobeDigitalPublishingCS6/ContentViewer/AdobeContentViewer.air
Windows: C:\Program Files\Common Files\Adobe\Installers\AdobeDigitalPublishingCS6\ContentViewer\AdobeContentViewer.air
Note: If you don't have the AIR Runtime installed, double-click the Adobe AIR Installer file in the same folder as the AdobeContentViewer.air file to install it. If that version of Adobe AIR is out-of-date, you can get the latest AIR Runtime installer here:
http://get.adobe.com/air/