HTML, CSS and Javascript.
Every. Single. Day.
Use John Maxwell's "Rule of Five":
https://www.johnmaxwell.com/blog/the-rule-of-5-for-the-john-...
Pick five things to improve related to HTML/CSS/JS every day, and make sure to be consistent.
Another idea to get started learning about building applications is to start building things with a #nocode platform.
Here is a survey of some of the top platforms:
https://www.webase.com/blog/the-ultimate-guide-to-no-code-pl...
Also note that Webase itself is a no-code platform and is useful in learning how to build data models etc.
Best of luck!
So the first problem is to learn what to learn. When I was trying to teach my gf to code (she is also non-engineer) it was actually pretty overwhelming for me, because I needed first to give her a lot of what-is-what knowledge. E.g. how internet roughly works, what is server, what is client, what is db, etc.
At the end I bought some Udemy full-stack web development course for ~ $9.99, they are always on some kind of sale. That worked pretty well (although she didn't get very far, I have to push her again :D), because they explained everything from scratch so you can acquire that initial what-is-what understanding.
So I would advise you to first acquire that general kind of knowledge, understand the basic parts of web (development) and then dive into the specific technologies - you will have much better context of what are you doing and how it fits in the bigger picture.
I believe any course with a decent amount of stars/reviews would do well. Feel free to ask more here.
Hope this helps!
This way you can set up an: Accountability system -- as good as having HN or freecodecamp's Twitter beat you up for missing a day on the 100 day's of code challenge there is nothing more efficient than having someone in person that you can go to for help when you're blocked and begin to burn out after a difficult hurdle. This will also help you out in determining which end of the stack you want to end up in. It's so easy nowaday for everyone online to say "I wanna be a fullstack unicorn so I make the big bucks!!!!" ,but then you just end up being mediocre at 2 things, rather than focusing on front end or back end and really excelling in that area. A mentor will help you figure out what you're actually interested in and keep you focused.
Code review -- Not only will having a mentor help teach you best ENTERPRISE practices, but they could give you other ways to think of solutions rather than going onto a Udemy class where the instructor types some code and you regurgitate then eventually get stuck in tutorial hell. I uppercased enterprise here because most online courses teach you the easiest, least secure, and just show me a working website as fast as possible. That doesn't translate well into the professional world.
Way into a junior role -- This is the big one. If you truly stick with learning web dev and your mentor sticks with you and sees potential then you will have an easy way out of customer service. You won't be paid as much as if you had transitioned to a new company, because that is how our HR overlords work, but you'll have something that differentiates you from other self taught web dev's. Real world experience and references to boot.
All the best!