There are Sabbats - the main celebrations below - and Esbats which are usually full moons and new moons, though some covens only focus on the full moon. The Sabbat provides a time of reflection, to gather your strength and see how you can strengthen your character from each celebration to the next as the seasons change.
For more information on the Sabbats, go to Spheres of Light for your 2011 southern hemisphere exact dates and times.
Southern Hemisphere Wheel of the Year
Northern Hemisphere Wheel of the Year