It is used to light candles every night of the eight night of Hanukkah. The ninth candle, which stands higher than the others, is the shammash or servant candle. It is used to light the other candles. On the first night, you light two andles, three on the second and so on. The candles are lit from the right to the left.
Children get a gift each night after the candles are lit and dinner is over.
The Menorrha symbolizes the oil lasting eight days in the temple after the Macabees defeated the Syrians and drove them out of Israel. While waiting for the messengers return, the people found that it saved oil if they lit one wick from another, rather than start a new fire. This is how the menorrha started. Thus was born the celebration of the Festival of Lights, which celebrates the Macabees victory and also the Miracle of the oil lasting for eight days. This story is told in the Talmud, the book that contains all the laws of the Jewish religion.