In the previous lesson you were introduced to the major chord formula, I - III - V. The formula for a minor chord is I - bIII - V, thus the only difference between a major and a minor chord is the flattened third note.
e.g., Notes of the C major scale:
Notes of the C minor chord:
You will notice that although the chord type is minor, its notes are derived from the major scale, not the minor scale. Comparing the C major and C minor chord notes, only the III is different (i.e., E in C major as compared to E flat in C minor).
Now, looking at the E major scale:
The E major and E minor chords contain the notes: E:
Construct the following minor chords: Am Dm Gm Fm