On the first night, one light is lit and on every successive night, an additional light is added so that on the eighth night, eight lights are lit.
If one uses a menorah which has holders for eight lights: On the first night one kindles the light on the extreme right. On the following night, another light is added to the left of that and is lit first, followed by the light in the holder which he had lit on the previous night. On each night, an additional light is added to the left of the light which had been lit on the previous night. This new light is kindled first, followed by the light which had been lit previously. Thus one is always adding from right to left, but lighting from left to right.
The reason why we first kindle the light which had been added that evening is to show that the enormity of the miracle increased on each successive night.
The lights should be lit so that they are in an even line. The holders should be the same height so that one light is not higher than the others. The holders should also be placed in a straight line so that some lights do not protrude, and they should not be in a circle. There should be sufficient space between the holders so that the flame of one light does not join that of another and so that the heat from one flame does not melt the wax of another.
On the first night of Chanukah, three blessings are recited before lighting:
1. Blessed are You... Who has commanded us to kindle the Chanukah lights... 2. Who has performed miracles for our fathers...
3. She-hecheyanu [Who has given us life...].
On the subsequent nights of Chanukah, only the first two blessings are made. If one was inadvertently unable to light on the first night of Chanukah, then She-hecheyanu is recited the first time that one lights.
It is customary to light an additional light aside from the Chanukah lights. This extra light, referred to as the shamash, may be used to light the Chanukah lights and one may derive benefit from its light. The Chanukah lights themselves may not be used for any other purpose as long as they are burning in fulfillment of the mitzvah. Therefore, the shamash is lit so that any benefit derived is considered to be from the light of the shamash rather than from the Chanukah lights. To make it obvious that the shamash is not one of the Chanukah lights, the shamash should not be placed on the same level as the Chanukah lights. It is proper that there be another source of light in the home besides that of the shamash.
It is customary to refrain from using the Chanukah lights even to light each other. Rather, the Chanukah lights should be lit using the shamash or another candle.
When lighting the Chanukah lights, the entire household should gather so that the miracle which is being commemorated will be publicized. [Pirsum hanes, "publicizing the miracle," is an essential component of Chanukah.]
After lighting the first candle, and while lighting the others, one recites or sings HaNerot Halalu. When the lighting is concluded, Chanukah hymns are sung in accordance with local custom.