According to the chart at the bottom of page 38' if you have seleceted the flash to be off, it will stay "off" unless you have set the "MODE" to "Backlit" or "Beach/Snow".
(see bottom of page 12 for meaning of those symbols).
See pages 23/25 to see how to change MODEs.
Backlit is for situations when you take a picture and the sun if behind the subject.
Without the flash in a backlit situation your subject will be dark.
It is best to avoid backlit situations.
Beach/Snow is for when you are taking pictures on the beach or in snow.