Aeolian

If we begin by naming the notes in the C Major scale and then placing numbers beneath each note we have the following:

CDEFGAB

1234567

The Major scale generates 7 modes and they are named Ionian, Dorian, Phyrgian, Lydian, Mixolydian, Aeolian and Locrian.

C Lydian can be constructed as:

123#4567 or C,D,E,F#,G,A,B

C Ionian can be constructed as:

1234567 or C,D,E,F,G,A,B

C Mixolydian can be constructed as:

123456b7 or C,D,E,F,G,A,Bb

C Dorian can be constructed as:

12b3456b7 or C,D,Eb,F,G,A,Bb

C Aeolian can be constructed as:

12b345b6b7 or C,D,Eb,F,G,Ab,Bb

C Phyrgian can be constructed as:

1b2b345b6b7 or C,Db,Eb,F,G,Ab,Bb

C Locrian can be constructed as:

1b2b34b5b6b7 or C,Db,Eb,F,Gb,Ab,Bb

Notice that as you change from one adjacent mode to the next in the above list that only one note changes.

The next thing you need to do is to apply this information to the remaining 11 major scales and their respective modes.