I think the number of petals ca vary but the best way to tell them apart is looking at the stalks behind the flowers, in the female the stalk is much thicker and is swollen at the base.
The pollen normally transfers from male to female naturally but if flowers are not setting, you can use a small paint brush (artists) sabel or cammel and gently insert the brush into each flower and giving it a little wiggle. Good Luck Tbird+
As discussed on another thread, we call them zuchinnis here in the U.S. The female will almost immediately have a small fruit developing between the flower and the vine. It will also be laying closer to the vine than the male flower. As to what to do... just stand back and don't let the fruit production run over you... they are very prolific...