A: For that you need to access the Media Library list (Playlists, Albums, Artists, ...) which is on the right from the Playing Now (central) screen and scroll it to the bottom to the Sources entry -> tap on Sources -> press [+] button in the bottom panel:

• for SMB/CIFS: tap on Network -> Network View -> tap on network interface IP -> wait while Neutron enumerates network and shows found IPs -> tap on found end-points to browse their file system and select top-level music folder. By long pressing the IP entry you can alter username/password for it if that is required;
• for UPnP/DLNA: tap on UPnP/DLNA -> wait until Neutron lists your network devices -> tap on found device -> select top-level category or folder which guarantees non duplicate music tracks -> confirm for scanning.