For the complete series go to http://tale2tell.com/after-effects-basics-multi-layer-keying-series-5-tutorials/
This first tutorial goes through the basics of using Keylight 1.2 in AE and how to create a basic key. These tutorials use footage from www.Hollywoodcamerawork.com and I would recommend going to the download section to see the green screen plates. However, I would also urge you to have a look at this excellent site with may very useful teaching and learning resources.
