This diagram is a simple representation of the notes in the parent scales of the modes derived from the A Major scale. Each mode is arranged vertically and adjusted for the position of the "A" tone within the parent scale. The provides a visual reference to the entire concept of modes and should help understand the concept. No guarantee.

You should be able to understand the relationship between the "A" Note position in the parent scale and the subsequent labeling of that mode within A Major.
An example would be the "A" note is the second note in the G Major scale. This would indicate that the G Major scale is the Parent Scale for the A Dorian Mode since the A note is the second tone of the G Major scale. The notes of the G Major scale and A Dorian Mode are identical. Just remember, you don't play from G to G, you play from A to A.
Modes for guitar