Much the same as Andrej's answer: learn HTML (what are the elements for? how should they be combined? how do they behave?) and CSS (styling the HTML). Jeremy Keith recommends some excellent resources at https://adactio.com/journal/11551
Then, I think the best advice I've seen in a long time... learn this one particular thing in JavaScript: css-tricks.com/video-screencasts/150-hey-designer… ...which is how to change a class when something is clicked. Attach all state to those classes.
If you know how to write valid, semantic HTML; and you know how to style it; and you know how to change the state of the DOM in response to the user... you can build most websites out there.
Tooling and abstractions will follow when you have done enough basic code to be getting annoyed with the repetition. Don't learn SCSS before you know CSS, for example. Don't get stuck trying to learn Gulp right off the bat, when you should be learning HTML (which requires nothing more than a text editor and a browser).
Note that web apps are more complex but you did say "sites" :)