If you haven't done this before (direct USB connection), you need to set up USB preference in the camera menu. Look in your menu under "Connecting to a Computer" and determine appropriate USB setting for your operating system. Follow the procedure for "Direct USB Connection". Make sure camera is OFF before connecting USB cable and computer is ON. After cable is connected, turn ON camera. If Mass Storage is selected for USB, PC will be displayed on top panel of camera. This info based on the D300 manual.