How to Play Octaves on the Bass Guitar

"Hi! I am Carl Shepard with expertvillage.com talking about different bass techniques and in the bass you can use an octave to give you a reggae sound and where you find your octaves is two frets and two strings apart from your beginning note. Say your beginning notes are in the fifth fret of A, just go two frets up, two strings up and there is your octave. So use you index here, pinkie here to give you that, and then usually use the root note to octave and then to the back root notes to give you a groove. And you can do that on any string and it is definitely a good technique to fill up some space."