Turn the exposure mode dial to P, S, A, M or one of the symbols representing the auto modes.
Auto The Auto mode is the simplest exposure mode available. The camera controls most of the settings, giving you limited control. The D90 is truly in a “point-and-shoot” mode. The exposure modes indicated by symbols are specialized auto modes.
Flash Off (lightning bolt) The flash will not fire. This can be useful if you're not allowed to use a flash or there is low lighting but you don't want to use the flash. In this mode the camera focuses ...