Hi, I think the problem you may have is that you'd need to code this in assembler and not BASIC. The learning curve from simple HTML to assembler (even on these old machines) can be quite steep.
If you've no programming experience (HTML is really a mark up language) then I would start with learning a high level language first to get the hang of some concepts. What you should start to learn first may be debatable. Whether to go with BASIC on the Beeb or something else.
Once that's done you could start by reading some old books on 8 bit machines and how they work at a low level and then start to look at assembler.
Starting off with Donkey Kong sounds a little ambitious. Don't want to be too negative, just I'd recommend starting off a little simpler
