Select the first icon on the left (Green arrow pointing from the Wii chip to the SD card).
If you already have a NAND file and need to extract or modify it, these tools are widely used in the homebrew community: MarioCube Repository Startup Disc NAND + Extracted nand wii download link
Downloading a Wii NAND (the internal flash memory of the console) is a unique process because every Wii has a tied to its hardware. This means that a NAND file from one console typically will not work on another unless you have the corresponding keys.bin file or are using an emulator like Dolphin. Select the first icon on the left (Green
Another method to play downloaded games is through an SD card or by using a USB loader. These involve transferring game data from a computer to the Wii's external storage and then loading the games through homebrew software like USB Loader GX. Another method to play downloaded games is through
console. Detailed steps for this are available on the Wii U Hacks Guide . This is specifically useful for Virtual Wii NAND with Dolphin setups to enable online play. BootMii Backup | Wii Hacks Guide
Here are some reputable sources where you can find a Nand Wii download link: