Guide to inject NAND Backup and play Online (Dolphin)
This guide is meant for those who have already installed Dolphin and want to use their own NAND backup instead of the default one provided from the install.
Now if you want you could play online right now. However, Dolphin's default NAND lacks some features. It's better to inject a real NAND so you can actually access the Wii Menu to make Miis along with many other features.
Before we do anything on the Dolphin side of things, you need to have a NAND backup (nand.bin file) of the desired NAND you want to use. You do NOT need the keys.bin nor the bootmii folder.
If you don't have a NAND backup, you can preform a bootmii backup to get one. There's plenty of tutorials everywhere online on how to do that, this thread is NOT a bootmii guide.
Once you have your nand.bin on your computer (doesn't matter where, as long as you know where it is located), its time to boot Dolphin.
Windows:
Launch your Dolphin.exe file
Linux:
Open terminal. Type dolphin-emu
Dolphin will boot. At the top, there is a tab called Tools. Click Tools. Then click the option - 'Import Bootmii NAND Backup...'
Browse your computer and select your nand.bin file.
Once completed (should only take a split second), click the Tools tab again. This time, click the option - 'Extract Certificates from NAND'. This should also only take a split second to complete. Alright, lets configure the button mapping on your emulated Wii Remote, as the default mapping sucks. At the top right you will see an icon that resembles a Classic Controller, click on that icon. Next to 'Emulated Wii Remote', is a Configure button. Click on that.
For the A button, there might be something like "Click 1". Right click on that button. A new window appears. At the large field at the bottom, delete the current value and put in "A" (capital A). Then select Apply and OK. Close the window.
Do this same procedure for the emulated Wii Remote B button, and change that value to "B" (capital B). Obviously, the A button on the keyboard will be the A button on the wii remote, and the B button on the keyboard is for the Wii Remote B button.
OK, select Tools tab. Click "Load Wii System Menu...." Wii System Health Warning now appears. Your mouse navigates the Wii Remote Cursor. A is for A, B is for B. Go into your Internet settings and make a new WIRED connection. Once successful, deny the Wii System Update offer.
And that's it! The Wii can now access online game services and you are running on your real NAND instead of the default.
Congratz!