Programming

Like a lot of people mentioned, there's a few good things you could start with, but C is probably not one of them. At my old job I ran a course for software engineer 2s to go over C, and even they had some struggles with it. If professional engineers struggle with C, it's maybe not the best starting point. Even C++ might be better, but still adds a lot of complexity that isn't necessary to know as immediately as the beginning.

Whenever people ask me where to start, I say python. It gives you a relatively tame taste of environment setup, and can run code very easily and flexibly. Its type system is flexible enough to make a user aware of it, without it being as rigid as C or as vague as javascript. Because there's enough libraries that are easy to pull in, even a beginner can start building useful programs without having to know how to build something equivalent to those libraries themselves.

Obviously if you want them to make websites, javascript will be necessary eventually, and isn't a bad place to start. If you're going purely for CS knowledge, I do think python is a little better; going from python to JS is probably easier than JS to python.