The "BELT" is actually preinstalled around the large ring on the underside of the turntable platter [please see image below].

If you can not seem to find the belt under the platter...please check thoroughly in the box and other packaging material, as it might have fallen off. If you still are unable to locate the belt...please contact the Technical Support department at 401.658.3131 or support@numark.com, and they will be happy to send one out to you.