Use your new alphabet (that's the one on the second line) to write a message. To write your message in code, find each letter that you want to use in the top row, and swap it for the one underneath it. So, for example, the word 'hello' would be written as 'bmggk'.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
P Y R A M I D B C E F G H J K L N O Q S T U V W X Z

As long as the person receiving the message knows the keyword, they'll be able to read your message to them.