As mentioned, you should pick up a language like Python, C++, etc. HTML and CSS are helpful for getting the look of a website down, but if you want to add some more functionality for the website (for example, when you click a button, your comment is saved), you'll need to pickup a language like these. Think of a problem in your life you could solve by coding, then start working through it with your chosen language. If you're successful, you'll come out of it with experience and a new tool to use! If you aren't successful, you'll still have learned a ton from the experience!
Once you feel comfortable with a programming language, I would start reading up on common algorithms and design patterns, which is knowledge you can carry with you into any programming language, product, or company. These will build the foundation for your work going forward, and will usually inform you (at least partially) on how to solve common problems.