If you ran one x 100w bulb it would be using 100w, if you ran it for an hour it would have used 100Wh (Wh = Watt Hours).

If you ran 10 x 100w bulbs they would be using one Kilowatt (1000watts is the same as a KiloWatt or KW), if you ran 10 x 100W bulbs for an hour you would have used one KiloWatt-hour