Well, for one you always light a lot of candles at home and eat a special cake called "Lussekatter" (which literally means "LuciaCats", but don't worry, cats aren't an ingredient ). Then, at your work or school there is usually a little concert, where girls are dressed up in long white gonws with glitter ribbons in their hair, one Lucia with a crown with candles in her hair, boys with a long hat with stars on it, boys and girls in santa like clothes and boys dressed up as gingerbreads. Songs are sung, mainly in Swedish of course but also one old song in Italian.

Here is a picture (but you can only see the Lucia, the girls with glitter ribbons who are called "tärnor" and the boys with the star hats):



And here's two more where you can see everyone (but it's small kids so the candles are electrical for safety's sake):