I bought a sharpening kit - guides and files - from a DIY store. Relatively easy to use.
http://www.opeconsult.com/chainsaw.htm
http://www.logbuildingtools.ca/images/pic76b.jpg
http://www.youtube.com/watch?v=dkpMwpzE48Q
http://www.youtube.com/watch?v=_qhwQy8jTHg
http://www.youtube.com/watch?v=_Lj3fNRdjvw
Good luck...
Peccavi
May 2010