good question!

http://www.trade-schools.net/devry-university/web-graphic-design.asp

or type: distance education web design in you local google search text field

I agree, you can do it all by just starting to read the free tutorials available online. We've collected some that were helpful to us, good luck:

http://www.mimoymima.com/resources/learn.php

Just one more idea to add: Start out with a project in mind. Start with a sketch or a mockup in a graphics program. By having a project in mind, the problem becomes less about "how do I learn Web design"-- a large and rather non-specific task-- to a number of smaller, more managable "how do I do this" questions. (Or as you progress, "how do I fix this" questions, most likely :) ) It also gives you a reachable metric to know how well you're progressing.

If you're staring from square one, with no HTML knowledge whatsoever, start simple. Make a static web page or site (one that doesn't change dynamically based on viewer input). There's a lot to learn just in the subjects of HTML and CSS text styling/positioning. Once you get that down, you might want to take the jump to JavaScript-- at which point you'll go from HTML/CSS markup-- essentially making "display notes" for text-- to changing those elements programmatically to introduce interactivity.

Just a tip, too-- although a lot of sites have them, you might not want to delve into coding your own dropdown menus until you're further along. They seem simple, and by all rights they should be (I'm looking at you, W3C), but I think more collective developer hair has been torn out in pursuit of perfecting the cross-platform dropdown menu than any other web-code task. (Well, except maybe multiple columns sans tables...)