I can not find where to look to see how much space is left on my WD book live
Connect the hard drive to a USB port, right click in My computor, highlight the drive and click properties.
It’s a network drive, not a USB drive !
In the My Book Live dashboard, go to system settings, and choose General, and look at USAGE.
The complete manual explaining that is here
http://www.wdc.com/wdproducts/library/UM/ENG/4779-705058.pdf