Please Help! Backup MBL to MB via Time Machine

I’ve seen this posted in two other locations on these forums with no answer. I want to backup my MBL with my MB external. Does anyone know how to do this? I want to use my MBL as the primary hard drive to access all my data. I want to use Time Machine to back up the MBL to a WD My Book 1.5 TB. Any help would be greatly appreciated!

As far as I know Time Machine can only be used to backup the internal hard drive in your Mac. To backup the files from the my book live to the my book you can do it manually or with a 3rd party software.