Like the 3DS has Gateway, and the Wii has the Homebrew Channel, where do I start with homebrewing? Do I have to learn C++, C#, etc. or is it more complex then that. I want to help with homebrewing the Wii U.

Sorry, but there is no native Wii U homebrew yet (well there is a browser exploit, but I don't think any documentation on how to code for that exists, and it only works on FW versions < 5.2.0). You can use Wii homebrew through the virtual Wii mode however.