Your connected hard drives to your WD TV SMP can be mapped to your network from your PC a couple of ways. I have done them both. From windows, open your network folder and click on your WD TV SMP icon, provided you have already, added it to your network. When your next window opens, it should show any drive connected to the WD player, whether it be USB thumbdrive or a USB hard drive. Right click on the drive you want to share and in the menu will be a selection for "map network drive", click on it and a new window opens which allows you to assign a drive letter or select specific files or folders on the drive to share, if you don't want to share the entire drive, check off box for reconnect at logon and then click finish. Your drive should now show up on your PC under "My Computer", under "Network Location", if you see it there, it is now available to your home network. This is for Windows 7, other versions may differ slightly, but the steps are pretty much the same.
The other method is with a program called "WD Link", it is available from Western Digital's website here:
http://support.wdc.com/product/download.asp?groupid=117&sid=110&lang=en. Copy this link into your web browser and enter, will bring you to download page, where you can download and install it. It will give you a nice GUI one place method to do the same as above.