Relative majors and minors have the same key signature, e.g. Am is the relative minor of C major and contains no sharps or flats. So the key signature of Am is the same as C major.
If a song ends with a minor chord it is most likely to be in a minor key. E.g. Harem Dance on page 22 ends in an Am chord and is in the key of Am. Minka on page 29 ends in an Em chord and is in the key of Em.
You will notice that the notes in the E natural minor scale are the same as the notes in the G major scale. E minor is the relative minor of G major and shares the same key signature (one sharp, F#).
E minor is the relative minor of G major
To play the Em chord use the first, third, and fifth finger of your left hand as shown in the diagram.