http://audacity.sourceforge.net/
you need an quarter inch to eigth inch adapter, quarter inch is the guitar cord size and eigth inch is headphone and computer jack size. you can get them at any
radio shack. Instead of an adapter i got a cord that has is quarter inch on one side and eigth inch on the other. i used to use an adapter, but because of the weight of the guitar cord and i had a little wear on the jack so i switched over. this is the cheapo way, above is much more professional.