a 12-string is played the same as a 6-string. the difference (besides the obvious extra 6 strings) is that each of the normal EADGBe strings has a string of the same note right next to it that is an octave higher in pitch, except for the high b and e strings which have the same pitch. The sound it produces is fuller sounding and almost like a chorus effect is present. Do a "google" search for 12 string guitar and I'm sure you can find alot more information on 12-strings.