I am talking about the regression method that measures the impact of several layers of independent variables upon a dependent variable.
The Centre for Multilevel Modelling has free online tutorials for multi-level modeling, and they have software tutorials for fitting models in both their MLwiN software and STATA.
You will probably want to check out all the questions with the multilevel analysis tag here. You will find many other suggestions for books and resources.
Also Harvey Goldstein has an online book, but I would suggest you check out the Centre for Multilevel Modelling first.
I warmly recommend Doug Bate's book