It sounds like you are having trouble tying together all the technologies and how they work with each other.

Here are some ways I learned quickly:

• Develop a mental model of how everything works together. For example, you know that HTML is the document on which CSS is used to style. You know that jQuery is developed on top of Javascript, both of which are used to alter the behaviour of the document. When you learn something new, consider how it fits into your existing model of how things work.
• Experiment with code daily. Create a folder on your local machine to experiment with things; and experiment A LOT. Encountering a new technology can be overwhelming. It helps to create your own project folder, and experiment with the code from the ground up. The more you code, the better you will become.
• Continuously read and research best practices, and again experiment with these in your experiment folders. Remain subscribed to top web development content providers like blogs and YouTube channels.

A word on WordPress and Learning
If you are now learning how everything works, I suggest you develop without a CMS like WordPress. Yes, you can get cool features up and running easily with WordPress, but you will not have a good understand of how they actually work, without having a solid understanding of the technologies which built them. I recommend that you get well-acquainted with Javascript, since this language will make it much easier for developers to adopt new libraries, and granularly control existing ones.