Do I need the 'privateold' folder?

I followed the instructions but one thing still bothers me, the wiki mentions that I need to rename a folder "private" to "privateold" but it doesn't exist at all on my SD card. Do need to install smashstack and homebrew? I already erased the stages so there isn't any to copy or erase.

Also, will the latest version of hackmii work for the wii?

The wiki suggests that you rename the private folder if you don't want to lose the data the wii stores in that folder and because it would interfere with smashstack but if you say that the folder doesn't exist then that means you haven't saved anything wii related to your SD card so you should skip that step.

smashstack is an exploit meaning that it just allows you to run homebrew code on your wii and it can't be installed, on the other hand the homebrew channel can be installed by using the latest hackmii installer. It is up to you if you want to install the homebrew channel but we warned that if you do so your warranty will be void.

Finally, yes the latest version of hackmii works on the wii

I suggest you read the following wiki articles before doing anything:

Smashstack
Homebrew Channel

- If you want to restore your SD Card Wii Data from before smashstack, delete private and rename privateold back to private.

If you don't have the folder "private", ignore that step.