What are exactly the "basics" of html , css?

So , almost 3 weeks ago I've just started to learn HTML and CSS with the help of Head First html , youtube tutorials, freecodecamp and codecademy. After 3 weeks of constat studying I am certain that I can build simple websites , like tribute page , product landing page and survey form and I can make my web site online with Filezilla. My question is..what should I know exactly so I can move up to JavaScript? Am I good to go?