This document provides instructions for using a dictionary code to encrypt and decrypt messages. It explains that a dictionary code uses a 3-part number system to indicate the page, column and word position in the dictionary. It gives an example code of 191106, meaning page 191, column 1, word position 06. The instructions emphasize that numbers less than 10 need a leading 0 to make the code 3 digits. Students are directed to practice decoding a sample message and encoding the answer using the dictionary code.