If you do not own a Wii, your options are severely restricted. Dolphin a NAND to run the Wii System Menu or any WiiWare/VC titles. However:
If you search the web, you will find websites offering a one-click .bin file. Ignore them. They are illegal, dangerous, and often broken. wii nand download dolphin
Select the first icon (Green arrow pointing from the chip to the SD card). If you do not own a Wii, your
Pick an option and I’ll produce the publication. Ignore them
A: On your Wii, go to the Wii Data Management menu and copy your save files to an SD Card. Then, in Dolphin, use Tools -> Import Wii Save and select the .bin files from your SD card.
The most "interesting" part of the NAND story is the online battlefield. In the early days, users could easily play online using auto-generated NANDs. However, this led to a plague of cheaters who could simply generate a new identity whenever they were banned.