you could play all the notes from the D string on the A string by playing 5th fret, but I personally think it sounds better with the open D note. the 5-6-7 run at the end is a triplet. 1 . 2 . 3 . 4 . | 1 . 2 . 3 . 4 . | 1 . 2 . 3 . 4 . | 1 . 2 . 3 . 4 . | e|-----------------|-----------------|-----------------|-------------------| B|-----------------|-----------------|-----------------|-------------------| G|-----------------|-----------------|-----------------|-------------------| D|--------0--------|--------0--0---0-|----------0------|-------------5-6-7-| A|-----------------|-----------------|-----------------|-------------------| E|-5-----5---------|---------5-------|-5-----5---------|-------------------|