Refreshing mPad


I have a Bryston digital combo and use mPad on my iPad to access my music. Is there a tutorial anywhere explaining the mPad features? I'd like to better understand the "Refresh local cache" and "Update database" features.
When I haven't listened to my system for a few days, my iPad doesn't show all the album and artist info.  Hitting "refresh local cache" 2 - 3 times seems to restore the info on my iPad.  I also hit "Update database" but not sure if doing so actually accomplishes anything. Can anyone out there educate me?
rockyboy