We light the Menorah every night for 8 nights. To remind us of the miracle that happened over 1000's of years ago. The miracle was the we found a pitcher of oil that would normally last about for one candle, and that oil supplied all the oil for all the eight candles, after the Beit Hamikdash was destroyed. Hanukkah is a Rabinical commandment. One lights candles after three sufficient starts are out at night.