Input the HDMI cable into the HDMI output on your NVR, and plug the other end of the HDMI cable into the HDMI input on your television or monitor.
Please be aware that you must plug the other end of the HDMI cable into an input, like on a television or monitor, and not an HDMI output like on a laptop.
Once you have plugged the HDMI cable into both the NVR and the television or monitor, ensure the NVR is powered on by attaching the power connection to both the NVR and a power outlet, and that the proper HDMI input is selected on the output device.