Yes. I use this one for other language, I find it quite good at explaining: https://www.geeksforgeeks.org/c/c-programming-language/
The thing is coding wii homebrew require C knowledge + knowing wii specific library. That's why I suggested...
Book. I can't recommend any specific since the ones I read are in french. But pretty sure, there are a lot of good books to understand the basics. C or C++ aren't the easiest languages to start by the way. It also depends how you learn generally...
