Light Candles:
Girls and all women that are in the house (or if there isn't a woman in the house, the head of the household), should light candles 18 minutes before sunset - see this link for the exact time - and recite the following blessings:
Rosh Hashanah Candle Lighting Blessings - Both Nights
1) Bo-ruch a-toh Ado-noi E-lo-hei-nu me-lech ho-olom a-sher ki-de-sha-nu be-mitz-vo-sov ve-tzi-vo-nu le-had-lik ner shel Yom Ha-zi-karon.
Blessed are you, L-rd our G‑d, King of the universe, who has sanctified us with His commandments, and has commanded us to kindle the light of Shabbat and the Day of Remembrance.
2) Bo-ruch a-toh Ado-noi E-lo-hei-nu me-lech ho-olom she-he-che-ya-nu vi-kee-yi-ma-nu vi-hi-gee-an-u liz-man ha-zeh.
Blessed are you, L-rd our G‑d, King of the universe, who has kept us alive and sustained us and let us reach this time.
Yom Kippur Candle Lighting Blessings
1) Ba-ruch a-tah ado-nai e-lo-hei-nu me-lech ha-olam asher ki-deshanu be-mitzvo-tav ve-tzvi-vanu le-hadlik ner shel Shabbat Kodesh VeYom HaKipurim.
Blessed are You, L-rd, our G‑d, King of the universe, who has sanctified us with His commandments and has commanded us to kindle the light of Shabbat and Yom Kippur.
2)Ba-ruch a-tah ado-nai e-lo-hei-nu me-lech ha-olam she-heche-ya-nu ve-ki-yi-ma-nu ve-higi-a-nu liz-man ha-zeh.
Blessed are You, Lord our G‑d, King of the universe, who has granted us life, sustained us, and enabled us to reach this occasion.