Be sure your system is connected to the Internet, and tap the Nintendo eShop icon on your device.
Select the "Purchase" option for the game you’d like. You may add funds using a credit card or by redeeming a Nintendo eShop Card.
Follow the on-screen instructions to download and play your new game.
The Nintendo eShop for Wii U and the Nintendo 3DS family of systems is your one-stop entertainment shop. Get exclusive content, game demos, applications (including video on demand services*), and more— delivered directly to your device.
*Paid membership may be required.About the eShop