Extract then copy and paste to your roms folder on your usb/sd whichever you choose to store your games on .....

If you have problems loading roms from USB try this version of Wii64 link for actual emulator is below.

For the Wii64 beta 1.1.1

https://sites.google.com/site/wiisixtyfour/files/wii64-beta1.1.1.zip

I believe Roms can be used on the CPU emulators also, however I have never tried.