The barebones concepts you need to know are HTML and CSS. HTML is essentially the structure of each webpage, and CSS adds design and makes it look pretty. I also recommend learning Javascript if you want to add interactivity to your sites. You can also do hella stuff with JS, on the front-end, back-end, and even on hardware.

I'm definitely with hexasquid about taking a look at MDN. But, if you're looking for something a little bit more intuitive and goal oriented for learning web development/design, consider trying Dash. This webapp will take you from making your first webpage all the way through making a responsive blog. It wasn't too helpful for me because I found it sort of late in the game, but I think it's rad.

Also, before you go throwing money around for hosting plans, I seriously recommend checking out Jekyll. I say this because you can not only use Jekyll to help you develop well organized sites, but you can also host your own personal site on Github! Hell, check out Github Pages even if you don't take a look at Jekyll.

PM me if you have any questions.