One area to the right of the bridge is played in a sort of plucking motion. The other area is used to bend the pitches by pressing the excess strings. The instrument is not tuned in a Do Re Me fashion, which to me actively fights my musical instincts, but in a refreshing and exotic way.
The song Sakura Sakura is probably the most recognizable song on the koto.
Here is a beautiful version played by Kimio Eto
Here is a girl playing the koto watch how she plucks, and bends the strings.