This website
High Lift Systems: Introduction could give some basic understand of high lift devices (slats, and flaps). Slats increase the maximum lift coefficient and the Angle-of-Attack where this maximum lift coefficient
occurs, flaps increase the lift coefficient at zero Angle-of-Attack.
I can also recommend the NASA study "High-Lift Systems on Commercial Subsonic Airliners" (
http://ntrs.nasa.gov/archive/nasa/ca...1996080955.pdf)