Known more commonly as Imbolc, Imbolic, Oimelc and Lupercus it falls around February 1/2(traditional) or February 4(actual-when Sun is 15deg Aquarius). It's the Festival of Lights-celebrating the return of the Sun.
This is also Brighid's Day-celebrating the Triple Goddess Brighid in her maiden aspect. She is Goddess of healing, inspiration, fire, fertility, household and smiths just to name a few.
Imbolc also marks midwinter as it has been six weeks since Yule and is six weeks until the Spring Equinox.
This is a time for cleaning, purification(home and body), planning our year's garden, blessing and planting seeds indoors (well for most places, the most northern US states and parts of Canada usually have to wait until closer to Ostara before planting seeds). We honor the Goddess in her Maiden aspect. On the eve of Imbolc, one tradition is to put a lighted candle(some traditions use red) in every window to help welcome back the Sun. Now is the time to make candles for the coming year!
Colors: White, Black, Green and Pink; although elemental colors (red, blue, yellow and green) are appropriate as well The golds and yellows of the flame are also appropriate. I picture the color scheme as having the slightest hint of color, a tempting sign of the beautiful colors yet to come as the year progresses.
Decorations: a bundle of three ears of corn symbolizing the triple Goddess hung on the door. ( I re-use my Indian corn decoration); candles (obviously! *g*); Sun wheels;
Foods: Anything round like cakes and golden such as pancakes and crepes, whole grains, milk and other dairy. Other options are spicy foods-to bring some warmth into this cold (for many of us!) February day. Seeds-which represent the seed of growth that has been or will be planted.
Feast recipes can be found here
Activities: Make candles, Singing, Making a Brighid's Cross; Burning the greenery from Yule to banish Winter
and usher in Spring, leave an offering for the fairies and/or Brighid-a dish of milk, buttered bread or some cake.
A great time to begin your Spring cleaning and purify your home. Cleaning the hearth and laying a fresh fire is also done at this time (and time to burn those leftover (or compost!!!) Yule greens if you didn't burn them at Twelfth Night!).
Clean and consecrate your magickal tools and work areas as well as your home. Imbolc, for many, commences their Spring cleaning.
Oimelc/Imbolc is also a day for women to spend time together. Mothers, plan a day of activities with your daughters. Women, spend the day with girlfriends, sisters or your mother or grandmother. Honor the Triple Goddess Brighid with your day's activities.
Some Celtic traditions make Brighid dolls (or save ones they made at Mabon) and Brighid beds or wheels.