http://www.yogabasics.com/
A guide to yoga practice

http://kidshealth.org/teen/food_fitness/exercise/yoga.html
Yoga for teens

http://www.holisticonline.com/yoga/hol_yoga_home.htm
Very useful information about yoga - types, benefits, exercises, poses, etc.

http://nccam.nih.gov/health/yoga/
National Center for Complementary Alternative Medicine (NCCAM) tells you about yoga practice.

http://en.wikipedia.org/wiki/Yoga
Read all about Yoga in Wikipedia

http://www.yogajournal.com/
Website about Yoga poses, meditation, Life

http://www.yoga.com/
Learn where to buy equipment (clothes, mats, etc.), books, videos, etc. about yoga

http://www.yogasite.com/
Website about equipment, DVDs, wholesales, etc. about yoga