Fetch user name from a module.

Fetch user name from a module.

I am trying to send a cliq message in cliq that should have the creator user's name, the modified user's name
There is a Created by field (System) in a books custom module. My requirement is to show the created_by user name in the cliq message. Though I have a flow, it throws the Createdby ID.
I was told by zoho flow to use the fetch function and then MAP. I am not well-versed with such a thing. 
Can any one assist me?