try this way..
browse - this should bring up a list of drives it can see..
in your case look for..
external storage.. ( mine is on the Windows network (SMB))
click into your music folder....just to the main..i.e music
and it should take you back with a screen that has
this stage you can name it if you want..
then hit ok..
then you should see it..
as to documentation..being open source...not a lot round at moment..
try heading to XBMC.org...
I am running both the Android ( Mediabox) and the Windows -( laptop ) versions..to see how they compare..
both going into separate HDMI inputs to TV..