The A natural minor contains exactly the same notes as the C major scale. The difference is that it starts and finishes on an A note instead of a C note. The A note then becomes the key note. To highlight the difference, the degrees of the scale as they would relate to the A major scale are written under the note names. Notice the flattened 3rd, 6th and 7th.
Here is the full fingering for the A natural minor scale in the open position, moving up to the high A at the 5th fret on the first string. Learn it from memory and then play it with your eyes closed, naming the notes out loud, and then naming the scale degrees out loud.
This melody is derived from the notes of the A natural minor scale and is therefore in the key of A minor. Notice that this melody sounds "sadder" than most major key melodies. The accompaniment to this song is a two bar fingerpicking part. The first bar is a new pattern and the second bar is pattern 3 which you learned in Lesson 12. The full accompaniment is written out in example 135.
Here is the accompaniment part. Take it slowly at first until you can play the whole thing clearly and evenly. You could also record yourself playing the accompaniment and then play the melody over it. Take care with the final beat of bar 16. These notes are played with the 3rd and 4th fingers at the 5th fret on the first and third strings. The 3rd finger will already be on the third string as part of the A minor chord, so you simply slide it up from the 2nd fret.