During the Festival of Chanukah we light the lights of the Chanukiah (8-branched Menorah) and connect to the energy of the miracle of the oil that burned for eight days. Seven is the number of Kedushah (holiness) within nature, eight is the number of transcendence. The spark within us (the soul) is connected to the Light of the Ein Sof (G-d). The purpose of lighting the Chanukiah is to realize that we are all flames on it and through the kindling of the lights, we focus on the light of our soul and on our mission of being "a light unto the nations."
Please note that each night we will have Arvit For Chanukah during which we will kindle the lights of the Chanukiah. The only exception to this is on Friday afternoon, we will kindle the Chanukiah and then the lights of Shabbat at the end of the Minchah (Afternoon) Service.