For most purposes you can safely ignore the W3C, and this particularly applies to their edicts on Cascading Style Sheets (CSS) and the <FONT> tag. The only reason I'm mentioning them at all is because you may hear that they have "deprecated" the <FONT> tag, which means they don't want you to use it. They want everyone to use CSS instead, which is far more complicated. CSS is just the thing if you are a professional designer creating a megasite with hundreds of pages, but for the likes of you and me CSS is way over the top - the <FONT> tag is much less hassle. Fortunately, although the W3C would like to abolish the <FONT> tag, there is absolutely zero chance that the browser manufacturers will stop supporting it, because there are literally millions of sites that use it, and any browser that didn't display them properly just wouldn't get used. It would be commercial suicide. So if someone tells you that you "ought" to be using CSS instead of <FONT>, just ignore them. Politely.
The easiest way to get some motion on a webpage is to use animated GIFs, like this skydiver. If you are feeling really adventurous (and you have a graphics package that supports it) you can make your own, but there are thousands lying around on the internet, free for you to use. Just go to a search engine and search for "animated GIF" - that's what I did. They are very easy to use, because you simply display them with the <IMG SRC> tag, just like a still picture. Do be aware that they are a lot bigger than a still image of the same dimensions, though, because an animated GIF is essentially a series of slides that display in turn, and all these pictures are included in the one file.
Another hugely impressive technology for websites is Flash, from Macromedia Technologies. It can do cartoon movies, sound, interactive games and all kinds of good stuff. Your visitor needs the Flash plugin, and although a lot of people have it, there are also a lot who don't. So if you do use Flash, make sure your site also works without it. One drawback to Flash is that it tends to be a bit bulky, so it can take a while to get started, especially if your visitor is connected to the Internet with an ordinary modem. Doesn't matter how good it is if they get bored waiting for it to download and leave before it starts.
If you want more than just musical notes, you need to use a recording rather than MIDI. The trouble with using recordings on a web page is that they tend to be very big. Even a few seconds of audio is likely to be hundreds of K in size, particularly in the ubiquitous .WAV format. Again, you can invoke a .WAV file with an ordinary link (or the BGSOUND attribute of <BODY> - but don't, it will take forever to load).
The best alternative for sound is MP3. It works by compressing sound files to a much more manageable size, at the cost of some sound quality. MP3 is actually an offshoot off MPEG movie technology, and although some MP3's stream, generally it is used for high quality music which you download. I'm too lazy to write you an MP3 FAQ, so if you want to know more you'll have to hit the search engines!
Last, and in many ways least, you can have movies. Least because movies are enormous, and over any kind of modem dialup they have to be tiny, grainy and very short
As with anything else, don't get too carried away with special effects. Apart from style considerations, they tend to eat up webspace very quickly. A decent-sized JPEG or GIF will usually be no more than about 50 K, and even a fairly large page's HTML will almost always be under 20 K. Anyway, a well-chosen picture will often have just as much impact as something fancy.
I hope this has given you a few ideas. Have fun with it!