micropython code for voice Prompt Module with Integrated MP3

I am searching for a clarification of the serial communication instructions, specifically I need  clarification about the serial communication instructions.  I have not used UART or serial communication before. The documentation specifies two things:

-1-“CMD Command” that is the single byte and 2- “Reference instruction” that is seven bytes. Which is the proper code to send to this device?

Also, if possible,  please post a simple demo code to access my MP3 files on this voice prompter device.  I am using micropython and the Thonny IDE, or, separately an Arduino.