Hi Jonny,
In Windows 8 the music software automatically looks at your Music library defined in Windows Explorer. I haven't found a way to change it to look at a folder instead yet. To add locations to the library:
Open up Windows Explorer (Windows Key + E, or bring up your desktop and find a folder to open)
On the left under "Libraries", right click on "Music" and click "Properties"
In the dialog that pops up you can add/remove folders from the library. Only catch is the folder needs to be indexed by Windows Search (which doesn't support network drives from what I can tell, hence why I'm ditching the player already).
Hope that helps, Jake