As with any physical activity, trying to learn from words, pictures, videos, etc. just isn't the same as having an instructor there to teach things to you and make immediate corrections as necessary. You will probably be able to pick up some basic information about ballroom via the internet, but it's going to be hard to learn it without actually doing it, preferably with/from people who already know what they're doing. The best way to start is to find some relatively inexpensive group lessons at a college/university (their classes are sometimes open to the public) or dance studio near you and start there. Sure, you'll be spending a little money on it, but you'll be sure to get good instruction. Can't guarantee that by looking at web information.
However, if you want information on dance steps and such, you can check this site. It should have basic level syllabus figures for most ballroom dances and there's a variation of the week feature too, but that's often on the advanced side. Another site I'd suggest is
http://www.jps.net/adamd/dance/dancelessons.html which has links to a lot of different sites containing some sort of dance lessons on the web. I hope this helps, but do consider taking some basic group classes if you're interested in learning ballroom. It's really the best way to learn (well, private lessons are actually better, but start with group lessons).
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James Marshall
marshall@astro.umd.edu http://www.astro.umd.edu/~marshall 
