How should I start learning backend development for my app idea?

Backend development covers a lot, including programming, web servers, APIs, databases, authentication, security, and deployment. Pick one practical stack and learn the parts as you need them. For example, you could use JavaScript with Node.js and Express, along with PostgreSQL or MongoDB. The specific stack matters less than building something consistently with it.

Start with a small project instead of trying to build the whole app immediately. A basic to-do API is a good exercise: create a few routes, save data, retrieve it, and handle errors. Debugging those small pieces will teach you more than passively watching tutorials.