Learning - How do I check exposure levels

Hi guys,

My appologies for a basic questions but I am a new photographer and Lightroom 3 user and I would like to turn the setting on within development that allows you to view in red the amount of over or under exposure applies in the photo I am viewing once imported into lightroom. In my old software, when viewing an imaage, the photo displayed in red the level of under or over exposure, so I could easly adjust. How do I get this red exposure indicator in Lightroom 3.

Any help would be very much appreciated.

Thanks Biscuits