You can either use shutter priority, aperture priority or manual mode. Shutter priority will be easiest as you just set the shutter speed you want to use and the camera will set the aperture for you. I suggest that you set an ISO rather than setting it to auto. Cameras have a tendency to really turn the ISO up in auto even when it isn't really needed. Also, you will have to use a tripod or you will just get a blur.
