If you are new to yoga or returning to yoga after being away for awhile then the Introduction to Yoga class may be the class that you are interested in.
Check out the Ashtanga classes if you are interested in a vigorous pracice that will help you quickly increase your flexibilty, strength and alignment then this class will be for you. If you have been going to the gym and are looking for an alternative that will keep you fit and your mind engaged then Ashtanga yoga is for you.
Have a look at the Kripalu classes for a less vigorous style of yoga compared to Ashtanga. The poses are held for a significantly longer amount of time. If you are interested in a slower paced practice then Kripalu is for you.