Hi. There is a blog that I would recommend a free blog that gives a very good insight to the main supplychain processes in standard Dynamics AX.
Take a look at the blog http://www.dynamicsaxtraining.com/ that Volodymyr Myronenko is maintaining. I recommend all new Dynamics AX consultants and developers to look into this blog. It sure give a overall starting point.
Happy blogging.
/kurt