Yule is a celebration of the winter solstice. It was originally celebrated from late December through the beginning of January. It is a celebration of the end of one year and birth of the next. It is celebrated on the shortest day, and longest night of the year.
Some people think that the tradition of the "Christmas tree" came about with the birth of Christianity. This is not so. Celts, Germans, Greeks and several others were know to pick a tree to decorate their home with. They would choose their tree carefully, to ensure they got the best one. Evergreens were the tree of choice, because they are reputed to have mystical properties. They would often decorate them with flowers, fruits and nuts in the hopes of bringing about springtime.
The burning of the yule log is one of the most well known customs. Most often it would be the left over tree from the previous year. Some will use one that is gifted to them. Others will go search for the "perfect log" and keep it in their home to protect it for a year. Burning the log is a symbol of the return of the light (spring) and waning of the darkness (winter).
It is customary to rub your log with flour and douse with cider or ale as an offering, before burning it. Some also decorate it with holly or other greenery. You then burn your yule log and let it smolder till it is gone, and offer the ash to the earth.
These are just some of the traditions I have learned of yule this year. However you choose to celebrate is up to you. Love, light and blessings for the new year everyone :)