Start by typing your message into the input field. Then choose your preferred encoding method – common options include Caesar cipher, substitution cipher, or custom letter mapping. For custom mapping, follow these steps: 1) Create your key by assigning each letter a unique replacement, 2) Enter your key into the designated field, 3) Input your message, 4) Click ‘Translate’ to see your encoded result. Save your key somewhere safe as you’ll need it for decoding later.