Yule is one the eight festivals or Sabbats of Wicca. These Sabbats are our way of participating in the turning of the Wheel of the Year, of connecting to the seasonal changes.
With Yule, we celebrate and metaphorically bring about the re-birth of the Sun.
Yule is celebrated at the winter solstice as the rebirth of the Great horned hunter god, a representation of the rebirth of the sun. You can follow old traditions or make your own.
In most parts of pre-Christian Europe, Yule was celebrated at home with family, a small, private affair. In Nordic areas it was often celebrated with a great gathering, including feasting and drinking.
In Wicca, some people celebrate this Sabbat privately at home, while other celebrate with their Wiccan Group (or Coven) performing rituals ranging from simple to quite elaborate.
Many Symbols and traditions of Yule are very similar to those of Christmas.
Bringing an Evergreen Tree into the house: the Evergreen symbolizes the immortal Goddess, present throughout the year. Bringing the tree into the house is welcoming Her into your home.
Decorating and filling your home with Lights and candles: the lights/small fires on the candles symbolize the newborn Sun (or Sun God). Metaphorically giving Him strength and welcoming Him back to the World.
Feasting: Ancient people of Northern Europe would often slaughter a large portion of their livestock because most of the animals could not survive the harsh Winter, so this was a time of great abundance. Celebrating with good food seems to be a common theme to almost every kind of celebration.
Carrolling: in ancient times, carollers were called 'Mummers' and would go from house to house, singing and giving symbolic gifts.
The Yule Log is a way of participating in the transition from the darkness to the light.
The log would be wood sacred to the local people, often decorated with greenery and topped with three candles (tapers set into holes drilled into the top of the log, usually white, red and black ( representing Maiden, Mother and Crone). Ever notice these are Snow White's Colors?
There is enough information about various Yule traditions and symbolism to fill volumes of books (or web pages). This is just some basics, I encourage you to research Yule as history and remember that the symbols are metaphors. You can make your own special celebrations and take your own personal meaning from them.
Merry Yule and Blessed Be!