In addition to our own video tutorial on this topic, there is also an excellent video tutorial on YouTube over 4 minutes long with audio at
http://www.youtube.com/watch?v=2BOzMX5Mujw
Another, also quite good (it's always helpful to hear more than one way of explaining something) is at
http://www.youtube.com/watch?v=Fxm1MiTlYzM.
