The best way to get started in computer programming is to start coding and have fun with it. In addition to taking classes in HS or getting a technical degree, there are a lot of great and free online sites to learn how to code. More coding (formal classes or self learning) will only help you get better.
Start by finding a language that you are interesting in learning and try to learn it. As a beginner I would suggest a modern programing language like Java, Node.js, Python, etc.
Once you gain the basics and have a good foundation try coding challenges. There are a lot of sites out there that give a problem that you need to code the solution for. As a bonus several companies use sites like this as part of the technical interview process.
Learn to code sites (there are more out there):
Coding Challenges (one of several out there):
-Understanding the Basics
-One Language at a Time
-Whether you’re learning to code by following tutorials or by reading a book, you should always type along. Reading the code will only get you so far since it doesn’t help you to understand how the code works.
-You need to do a lot of programming, make mistakes, and fix them. This is the only way that you’re going to get better.
-Learning how object-oriented programming works is a perfect step after you completely understand the basics.
Hope this helps!
Here's a few rules for a starter
No magic numbers
One source of truth
Comment, comment, comment.
Look at other peoples code. You'll soon see what makes reading and maintaining code easier and harder.