what you need:
-WII
-gamecube controller
-sd card
-gamecube memory card(any type that wii reads)( i use mad catz)

Steps:
1) Go to link and download the file [ Register or Signin to view external links. ]
2)Now download the save file you want from [ Register or Signin to view external links. ] or copy from the sample folders.
3) Rename the GCI file you downloaded or took from sample folder and change it to something with two characters, they must be capitalized.
For example the gci file you downloaded is called blank.gci rename it to BL.gci
4) Put the .gci into your gc_saves folder ( make sure you have one .gci at a time)
5) Run the app through the Homebrew channel
6) Follow the prompts. (its gonna ask you If you want to copy the .gci file, press a.
Then a dump will show up, then press a. then it would say reset)
7) Reset

If you want to copy other .gci to your gc memory card. Remove the gci file you already have
in the gc_saves folder.
You can only copy 1 gci file at a time

If you want go to ".gci samples" folder pick a .gci rename it into two capitilized characters and
put it in your "gc_save" folder

I take no credit for making this tutorial.Credit goes to clincko.