You can't backup your own NDS games with M3 Simply. You can however put NDS Roms onto your M3 Simply very easily through drag&drop onto your microSD card.
Dude do U even read the replies?? He just wrote that U CAN'T back 'em up and as for extracting save games I think you need either an M3 Lite or another hardware alternative but the Simply can't do that. Read HERE for more.
you ccan download them from DS-ROM-NEWS. you won't be able to get your saves unless you have a slot-2 device, the simply is a slot-1 device.