You enter the message into a "SHA256" generator:
https://passwordsgenerator.net/sha256-hash-generator/
7E644881BCA767AB1CA65B6F74409D1CD4D8E48818F37F3B774788376D699D4C
So if you put in the message "How do I hash a message to put here?" into the textbox, you should get the hash in the previous message.
