When you bring the bucket in the house, carefully tip it over in the sink. The bottom of the bucket will then be on the top. Carefully, unmold the ice (you may have to run a little warm water over the bucket). When the ice is unmolded - chip a little hole in it. Pour out any remaining water. (Actually, the water will freeze about 1/4 to 1/3 solid, so there will be a substantial amount of water. Do not let the water freeze solid). Now you have a nice opening for the candle ~ set the candle in the bottom of the sculpture (which is really the original top). Does that make sense?
Have fun with it.