This progression is actually a 'musical hook' that gets used throughout our song. Note that the actual riff or figure is 4 bars long, followed by a 2 bar vamp on D Major. This is true EVERY time the riff is used later in the song, so bear that in mind as you learn this section! You may be able to 'feel' or 'hear' this before you can count it, in which case, lucky you.