That’s the website my high school used in engineering sciences classes to give students an introduction to HTML. I don’t see the point of your comment (I think it’s sarcasm, but I’m not even sure), can you be a little bit more constructive?
The point may be that OP's guide is not meant for high school/engineering students, it is meant for everyone. MDN's "introductory" sections have too many big words to be of use to laypeople.