When my son was 9, he made this Screencast to help other children get started and I think it's probably the best way to see how simple coding can be!
Once you have seen that, probably the best place to start is the help Section of the Scratch Website. http://scratch.mit.edu/help/ It includes lots of help and some lovely tutorials. After that, on this blog, have a go at the Making Your First Game tutorials. Once beyond that, Shaun The Sheep is happy to help.
If you have an iPad and a computer together, then David Phillips has made a nice app to help. There are also some excellent books to buy on Amazon. Super Scratch Programming Adventure and Learn To Program With Scratch