The same way you play a 6 or a mandolin. 2 Strings under each finger. If your fingering . You tune the main 6 strings as normal. Then the others except the B and High E are tuned an octave below,the B and High E are tuned to the same octaves ( pitch ) which gives a Rich Jingle Jangely Full sound. Ricks use the main strings reverse to many other twelves which give them another unique sound. Listen to many of the Byrds songs and you'll hear the sound. ( Played by Roger Mcguinn ) YouTube - Byrds - "Turn Turn Turn" YouTube - Byrds - "Mr. Tambourine Man" Featuring Bob Dylan YouTube - THE BYRDS "Eight miles high"