MQTT Shift over

Need some help shifting over to MQTT for my solar power system. following sketch on github. I have some understanding connecting thru MQTT but clueless on publishing data. an example for 1 of the voltage readings would be helpful so I can build on that.
For reading voltages and status for power inverter and solar panels on digital loggers PLduino · GitHub

Anyone have a clue why this error message is coming up? If so, is there a fix? I just finished uninstalling and installing Arduino because of invalis library errors then returned the libraries necessary to upload the code for my PLduino.

Arduino: 1.8.1 (Windows 10), Board: “Arduino/Genuino Mega or Mega 2560, ATmega2560 (Mega 2560)”

open C:\Arduino\libraries\TMRpcm_PLDuino\ Access is denied.

Error compiling for board Arduino/Genuino Mega or Mega 2560.

This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.