I don't want to blow your expectations, but HTML hardly is a language. Sure, it lets you create nice things, but to do some serious programming, HTML won't get you anywhere. For instance, the AntiOnline pages, although being webpages, don't rely on HTML alone: It depends on HTML, PHP, some form of SQL, and probably more, just for the web interface. HTML lets you make nice, static pages, with even some forms to have some kind of interaction with the user, but that's it.

If you really want to learn something you can use for future reference, don't start with a language at once - start with learning about the principles of "Object Oriented Programming." This is some sort of general idea for modern programming (much like 'transportation' is the general idea behind cars and bikes, traffic lights, etc). The source that learns you about OOP probably will do this using examples from a OO programming language, probably either Java or C#. One of those is an excellent way to start learning about programming - learning HTML can be fun and usefull, but there's practically no other function for it, besides webdesign.

Good luck.