My advice is make sure you have the programming fundamentals. Online courses are available - MIT offers great classes and free too. Taking some kind of accelerator or bootcamp might work for you too.
Supplement learning with doing projects. Create some things you want to play around with. I found implementing data structures was a good project while learning programming because it simultaneously helped familiarize me with the data structures and with learning programming. Add on some projects in the areas you're interested in. Chat app, video game, website, whatever. I also suggest reading official documentation for a language or library instead of a book on the subject. The official docs, if good, are a lot more dense and valuable. I taught myself python just by reading their official docs and it was the easiest experience I've ever had learning a language.
As you get ready for the interview I would watch YouTube videos that take you through mock interviews. Listen to questions, pause the videos, give your answers, then listen to their analysis. You don't always need to agree with these videos, but it's good stuff to think about.
I also highly recommend leetcode. I know some people look down on it but software interviews often have a component that is basically a leetcode question. I suggest solving 2-300 problems, mostly medium or hard, and making sure you can solve any medium or easy question, and explain it as you go, in under half an hour. If you get stuck YouTube is a good resource to see people explain leetcode problems.
I have also found it helpful to write a little log as you're learning or working on a side project. I take notes of major failures and ask, and then explain in writing, why that happened and how I can prevent it in the future. When you find yourself writing multiple entries in the log with the same explanation, you know you've found a costly error you need to correct!