The nds target is used to create a .nds file that can be run on a real NintendoDS or DSLite (using an R4 card or similar), or on a PC using the DeSmuME emulator.

To support this target DevKitPro must be installed. When it is not installed in its default location (C:\devkitPro) the Makefile.local must be copied to Makefile.custom and edited to reflect the directory it devkitPro installed in. The DeSmuME emulator must be placed in devkitPro/emulators/desmume.

All publicly available Nintendo DS documentation is essentially reverse-engineered by hobbyists. There are lots of resources on the web, but no single place where you can find it all. Some places to check:

• http://libnds.devkitpro.org/
• http://osdl.sourceforge.net/main/documentation/misc/nintendo-DS/homebrew-guide/HomebrewForDS.html

DesMuMe seems to be the most used emulator, but there are others that you could try, check this list of emulators