Imbloc is the time when we celebrate the earth's return to spring. Depending on the Wicca one follows, will determine the type of celebration.

In groups there are organized ceremonies where the High Priestess may light candles and offer wine and cakes to Brigid, this website offers an example.

A good history can be found here.

Being Solitary, I simply bring in my seeds for the year, place them on my altar and proceed with a calling of the quarters. After that, I light my candles and finish my ritual. I would love to attend a big celebration one day. Until that time, I'll practice alone.