Using the wheel involves two processes – enciphering and deciphering. Enciphering happens when you write a message using a code. Deciphering happens when you try to understand the message by cracking the code.
The secret to successfully using the wheel is the shift key. The shift key is a number that both the sender and the receiver need to know. For example, a shift key of 3.
To start using the wheel, first, turn the big and small wheels so that the letters in both are aligned.
Next, turn the smaller wheel following the key.
Then, write down the new letters from the small wheel that align with the big wheel after you’ve turned the key. For example, after turning the wheel using a shift key of 3, A will become D, B will become E, and C will become F. When enciphering a message, use these new letters to hide the message. For example, the word CAB will become FED using the new letters.
When the receiver tries to understand the message, he/she will again use the shift key to understand what the new letter combinations stand for.