Ijust did a quick google --
Yoga for Beginners
this seems pretty good to get you thru the basics, it explains what each move does, and gives you pretty explicit instructions on how to do it.
When doing your workout, the goal is to make the workout fluid, so that'll take some time til you get used to what the moves are.
I've been doing this for a little over a year, I am extremely type A personality wise, it took me a few months before I could really settle into and do it -- where my mind didnt wander to a piece of code that I had to write, or soemthing else that I needed to do -- It was hard for me to get into that space, but it's worth it -- its 40 minutes a day where the world just goes away. (not to mention it's helped immensely with chronic back pain, and I haven't had a migraine in about 3 months)