I first encountered the concept HTML in my 200 level in the university when we treated one borrowed course from the department of computer science. It was quite hard for me to grasp back then because I wasn't really into designing, coding or hosting stuffs at the time.
But around my 4th year, I had done several course related to HTML, so it was a lot easier for me to understand it well. I also had to use some online video tutorials to help myself out.