HTML won't get you very far if you're trying to develop games. HTML is primarily a tool for web development more so than game/software development, although it -can- be possible to make small text-based games in the browser, if your audience are 'kids', as you say, this sort of thing is unlikely to interest them for longer than a few minutes.

The same sort of thing applies for Flash. True, it can be useful for making browser-based games with some fairly good features and gameplay tacts, but the end result is, although good, rarely standalone as they require flash player to be installed on the recipient's computer.

I suggest you learn a more powerful language for coding a game with the capability to make fully stand-alone executables like C++ or a coding language created primarily for the purpose of what you are intending to do -- creating games, such as DarkBASIC Professional.

SS

Yeah, HTML can't do anything like that on its own, it's just a mark-up language. If you want to develop text-based games first, and have no prior programming experience, I'd suggest Python. The syntax is simple and understandable. The one thing is that the recipient's computer needs Python installed on it to run the scripts (it comes pre-installed on most Linux distros), unless you use the py2exe module to make an executable.
C or C++ is another good bet, but the syntax I find harder for beginners to get into. This is what I'd choose for 2D or 3D development, or some Windows applications.