There are many different types of programming, e.g. Web Page, Apps, ERP, System Programming, etc. You may need to find out more what you are interested on. You may have more explore when you entering the college.
However, you can start doing some relative simple programming, e.g. using Scratch to control some robot device, Python, etc. You can also try to do programming on games interface as well. It may be interested you.
When you enter the college, you will learn more on computing theory and have explore of different kinds of programming. At that time, you can find out more on different programming types and decide your career path.
Hope this helps! Good Luck!
Python and C++ are great starting points, and there's a good chance they will be in professional use for years to come also. Neither are a bad choice, Python being the more standard learner language these days.
Becoming strong in a programming language is not always fast, but going through a course is generally recommended (e.g. udemy) because it will ground you in the fundamentals and at the same time help you apply the skills through coding exercises. It's a marathon not a sprint. Going straight to trying to build end-to-end solutions as other ppl have recommended is OK, but be thoughtful that you are really giving yourself time to learn at least 1 language deeply.
In the end what's important is to the learning process, and finding an area that generally interests you to get under the hood is a good strategy to stay motivated. When I say "area", I mean for example web development, mobile apps, graphics, audio, data, ... the list goes on and on. The point is each area is usually stronger with certain languages. And even if you don't know for sure, that's completely OK, python is
Best of luck
On your own, you might want to continue building your skills at problem solving, debugging, and integrating other skills like database skills, graphics, gameplay mechanics, or data science stuff.
You might even want to try your hand at developing a Roblox game (dev tools are free if you know where to look) or Minecraft for Java mod (the game itself is not free).