Just installed Eden and no access to NAS drive

Hi - Can you help?

My set up is XBMC on a Media Center PC connected to NAS.

I have been happily using v10 of XBMC for a while and decided to upgrade to v11, Eden.

This worked fine - except if I go to play anything it says "Path not found or invalid".

So I assume I have to set up the password to my NAS drive?

If so, how do I do this? (I know I must have done this 2 years ago, but I can't recall or find the guide on this).

Many thanks, D