I'd like for someone to explain the 7 modes derived from the C major scale.
The seven Modes are named thusly. If you start with C, they are spelled as follows:
Ionian (1), or the Major scale: C D E F G A B C
Dorian (2), D E F G A B C D
Phrygian (3) E F G A B C D E
Lydian (4) F G A B C D E F
Mixolydian (5) G A B C D E F G (which is the most common mode for rock and roll)
Aeolian (6), or the Natural Minor scale: A B C D E F G A
Locrian (7) B C D E F G A B
A thorough explanation of how they are all used can be found in the Wikipedia entry entitled "Mode (music)".
My music theory teacher in college always drew the distinction between key and mode. His point was that there is not, properly speaking such a thing as a C major key or a C minor key. He said that key refers to the central pitch, or the root note, only. From the root note, or key, you build a scale or mode. So he would refer to what we call the C major key as "the key of C in the Ionian mode" and what we refer to as the C minor key as "the key of C in the Aeolian mode."