http://www.youtube.com is your friend. Search for ‘yoga’ in the how to section. Tara Stiles style http://www.youtube.com/user/TaraStilesYo… is very engaging. But gently does it!
Also http://www.yogatoday.com have a free weekly class.
If you can follow pictures and written instructions you could also try:- http://yoga.about.com/od/beginningyogapo…
You can get books from the public library too. That’s how I started. Went and sampled a class after that but I was the only guy there so I didn’t go back.
You are best off though just learning a few basic poses and learning to do them well before even considering any pretzel like moves. (Which you don’t need to do anyway.)