In each letter in a Cryptoquote, a letter stands for another letter.
If the encrypted text were FRA PIF XD FRA LIF,
then the answer could be THE CAT IN THE HAT.
F = T, R = H, A = E, etc.
Guess which letter should be in each box by typing a letter in a box
then clicking outside the box to see where else it would appear.
For more detailed instructions see the Cryptoquote Help Page