If these seem obvious, A) I am very sorry, B) you have the perfect mindset for going into this.
1) Don't stress out over this; we're just here to have fun.
2) Be scrappy; your code doesn't need to be pretty or optimized, it just needs to work.
3) Don't spend too much time on any one thing.
4) Be familiarized with your game engine of choice. If you aren't settled on a game engine yet, just use Unity. It's got great documentation and better tutorials, (I recommend checking out Brackeys on Youtube, his tutorials are great,) but how well you know your engine is significantly more important than what engine it is.
Anyway, it's great to have you, and I hope you have fun in the jam! Go make cool things!