actually, you might not want to use a flash.. they usually make the pictures harsh looking
the settings are really depending on the situation..and there are lots "in the dark"
set the white balance to the right lighting condition... or else you'll get an ugly cast on your photo
if it's outside... or if your subject is farther than 10 ft away... turn on night flash mode which will hold the shutter open longer to capture the background or otherwise far away objects. keep in mind that most built-in flashes have an advertised effective range of ~14ft and actual range of ~10ft. if you can mount your camera somewhere--on a trashcan, against a pole, etc--so that you can hold the camera steady then turn off the flash. if the exposure is too long and ends up looking shaky, turn the ISO up to 200 or 400.