How do you connect the nintendo ds to the nintendo wii

The NDS can link with the Wii but it is very limited. There are extremely few games that allow the DS to play with the Nintendo Wii. The NDS can also link to the Wii to download DS play games but that is about it.

Basically, when the Wii sends out the DS demo, turn on the DS and go to DS Download Play in order to connect and to download the demo.