What really helps with learning HTML and CSS is using a live editor, one that allows you to see the changes appear in the browser as you code them. I recommend Mozilla Thimble (https://thimble.mozilla.org/en-US/). You can create a free account, and do all your website development right there. Then just download the files as zip and upload them to the server where you are hosting. That's what I do. You can even publish your website and get a URL from Mozilla to access it from anywhere.
https://www.khanacademy.org/computing/computer-programming/programming#intro-to-programming
https://thimble.mozilla.org/en-GB/ (there are times when I like thimble a lot more than codepen)