If you've never programmed before I'd recommend starting at the beginning with something simple like Scratch. https://scratch.mit.edu/ Try the Tips section for some tutorials and you can study other people's projects for inspiration. It might look a bit childish but it will teach you the fundamentals of programming using drag-and-drop instructions.
Once you've got to grips with that you can move on to something like Python where you need to type the instructions in. https://www.learnpython.org/
And then you could move on to Unity. https://unity3d.com/ They've got a good tutorial section and there's a big community. Unity is what's used to make Autonauts.