Basically you turn off your pumps, raise the aperture to a high setting, and keep the shutter open as long as needed. Just make sure you use a tripod. If your camera has an aperture setting use that to adjust your shutter opening to the desired number and the camera calculates the best shutter speed.

if your camera has a white balance setting that let's you measure the balance, look into getting a neutral gray card to help get you colors right. I got one for Christmas and use for almost every pic now.