To form the Phrygian mode, take a root note, then go up a half step, a whole, a whole, a whole, a half, a whole, and up a whole to get back to the root.

So, for example:
E Phyrgian = E, F, G, A, B, C, D
A Phyrgian = A, Bb, C, D, E, F, G

Notice that the Phyrgian mode is the same as the natural minor scale but with a b2. For comparison to the major scale, it has a b2, b6, and b7.

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To form the Mixolydian mode, take a root note, then go up a whole step, a whole, a half, a whole, a whole, a half, and finally a whole to get back up to the root.

Example:
G Mixolydian = G, A, B, C, D, E, F
D Mixolydian = D, E, F#, G, A, B, C

Notice that the Mixolydian mode is the same as the major scale, but with a b7.


I hope this helped...