At this moment, when the family is gathered together, the woman may offer a silent or verbal prayer on behalf of her husband and children (in generations past, personal prayers in Yiddish called "techinot" were commonly said by Jewish women before doing a mitzvah and on special occasions).
A minimum of two candles are lit corresponding to the two expressions of Shabbat mentioned in Exodus 20:8 ("Zakhor," remember) and Deuteronomy 5:12 ("Shamor," keep or guard). Some women add an additional light with the birth of each child and continue lighting it throughout the years.
In most cases of berachot, the blessing is recited first, followed by the performance of the mitzvah. In the case of this blessing, however, the woman lights the candles first, and then pronounces the blessing, since once she has pronounced the blessing, she has accepted Shabbat restrictions upon herself, and therefore would be unable to light the candles afterwards.
Candle Lighting Times
The exact time for candle lighting is determined by Rabbinical authority and is known as Zmanim. A weekly Jewish calendar will indicate the time for your locality.