To pull this instruction page back up again in the project, click the circular rainbow icon. To encrypt a message/word, click on the orange button until it says "Currently on Encrypt Mode" unless it already says so. Then click the "Click Me to Decrypt/Encrypt" button and type in your desired message/word. To decrypt a message, do the same except look for the button to say "Currently on Decrypt Mode". Click on the "Click to set Cipher Key" to set the cipher key. Click on the instructions in the project to make the instruction disappear.
Credit to MrsGrieser The link to the background picture is here: https://www.google.com/search?q=caesar+cipher&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiLt_3ZhObfAhWnuVkKHbcsCN4Q_AUIDigB&biw=1366&