Chodesh tov! Rosh Chodesh Tevet is until Wednesday evening.
In prayer and in Birkat Hamazon (Grace after Meals) we now add a special passage for Chanukah ("Al HaNisim") and also a special passage for Rosh Chodesh ("Ya'aleh VeYavo"). There is a special Torah reading, and we say "Hallel" (Psalms of praise).
There’s lots of light, and many additions, blessings, and customs.
Have you noticed that Chanukah is the only holiday that crosses from month to month? All other holidays occur in just one month. But during Chanukah there's a sign of renewal - the month of Kislev ends and the month of Tevet begins.
May it be a good month and may we hear good news.