Making your website accessible and disability-friendly

I haven't found much on the topic. I'm self-taught in html and a tiny bit of css, so I really don't know much. However, I'd like to do what I can so that I don't exclude others. I found a website that gave a few pointers at: It's a bit hard to read on a computer like mine with 800x600 resolution, but the gist was that flash movies and excessive graphics make it tough for others to view your site. I try to limit graphics anyway for a clean look and for those with slower connections, but I came away from the website with the plea to label all my graphics with "alt" tags resonating. I've also noticed that my font sizes become scalable if I use size=1,2,3,4,5 etc. instead of giving an exact pixel definition. All that to say.... what other things can I do? Are there any websites that can explain in simple terms? (80% of what I know about coding I learned at html goodies, LOL.) I've noticed some websites offer alternate stylesheets, but I really don't know where to begin with that.