Since free will is about as easy as a philosophical problem in reductionism can get, while still appearing "impossible" to at least some philosophers, it makes a good exercise for aspiring reductionists, which they should try on their own - see the main page on free will.
These posts should not be read until having made a very serious effort on your own.
Related Pages: Consciousness, Free Will, Philosophy, Reductionism,
(Items in italics can be skipped if in a rush.)