How do you find what exercise is right for you when you can’t afford a gym and you aren’t sure if you’re “doing it right” when you follow a video or written plan?

Try different videos / workout plans, see what's easiest for you to start with and get used to that first before moving to more difficult stuff. And talk to a friend who's more into fitness, ask them to help you out with whatever troubles you! i'm sure they'll love to help 🙂