OK. First the SD card part:
create a folder called wii u, then apps inside of that, then tcpgecko inside of that. Download these files at https://github.com/BullyWiiPlaza/tcpgecko/:
tcpgecko.elf
codehandler.bin
then, go into the meta folder and download meta.xml and icon.png. Once you have those four files, copy all of them into the tcpgecko folder on your sd card we made before. Okay, that is the SD card part done! Now the computer part.
Download this: https://github.com/BullyWiiPlaza/JGeckoU/blob/master/JGecko U.jar?raw=true and put it in a folder (don't put it on the desktop because the program generates a lot of files that would make your desktop messy).
Now for the Wii U part:
O your wii u, go to wj44.ml, then scroll down to "kernel examples", then "homebrew launcher". After a few seconds you will be in the homebrew launcher. Load tcpgecko. Press the X button. You should land in the wii u menu. Load whatever game you want. Then, on your computer, wait until the game boots up, then open "JGecko U.jar" when the game is fully loaded. Enter your Wii U's IP address and click "connect". If everything went right, your computer should now be connected to your wii u, ready to send cheat codes to the Wii U.
Awesome. One more question do I need to homebrew my console?