I have a WD My Book Live (MBL) (1Tb) connected by ethernet to my router. I created two folders in the MBL, one for each PC. When I did a trial backup I was not given the option of where to save the backup. I could not locate the files on the MBL but I can restore them back to the PC.  They must be in a hidden area.  The folders I created are in the 'Public' area and can be seen from both PCs. 
I can't use the W7 backup option as I have W7 Home Premium which does not include the 'save to network' option.
The WD Smartware also does not give the option on backup location.
The NAS is a WD My Book Live 1Tb with WD Smartware software version 2.4.2.
I have tried the WD website and asked Mr Google to no avail.
Any help appreciated.

I'm running W7 Home Premium on both PCs and want to use the MBL NAS as a backup for both.