It’s the first site that comes up in my mind when someone ask me this question.
I am a self-taught developer myself, and what I used back when I started was Udemy. I choose a course that would teach me a full stack so that I would be able to work for myself eventually.
For 3 months I studied day and night, and afterwards got a front end developer job alongside developers with 20+ years experience.
The course I used is: The Web Developer Bootcamp - Colt Steele.
Learning with an online platform would be a good idea. Someone already suggested you go with w3schools. This one is best. You can try for it.