How to Start Building My First App?

Have you considered why you specifically want a mobile app rather than a mobile website? If it's mainly for content, a mobile website can function just as well and provide a quicker experience for users. Plus, there's less complexity since you wouldn't need separate versions for Android and iOS.

I'd suggest diving into hands-on programming. The theory can come later; just start building! Depending on your goals, you might want to focus on web development, especially if you're interested in startups. For practical learning, Frontendmentor is an excellent resource that helped me write actual code instead of just watching tutorials.

A great way to start is by using a framework like Cordova. It lets you take standard web pages and turn them into apps for both Android and iOS, so you won't need to learn complicated languages like Java or Objective-C right away.

Since you mentioned you have a MacBook, don't worry too much about the negatives. Many developers find they prefer working on a Mac over Linux or Windows, especially for app development. Just use what you have as it’s quite versatile for coding.