Anyways…
HTML/XHTML – basic markup language for creating static webpages. The first thing you should learn.

CSS – Cascading Stylesheets. A close second; these are used to change various aesthetic qualities of your pages, and apply it consistently across your entire site.

Javascript – A clientside scripting language. Used to add interactivity to your page, as well as any functionality that involves the website changing after it has loaded.

PHP – A serverside scripting language. PHP is basically used to determine what HTML will be sent to the user’s browser. For example, forums are made using PHP, in most cases. The php script is told which thread the user wants to view, and the php pulls the specific data from its database and outputs it into an HTML page.

AJAX – The combination of javascript and PHP. Since javascript is clientside (done by the browser, after the page has loaded) and PHP is serverside (done by the server, before the page has loaded), AJAX serves as the necessary bridge between the two. It uses javascript to send a request to the server for more data, and then uses that data to change the page around.

Flash – A mostly different can of beans. Flash is a medium for interactive web applications, with its own programming language (actionscript).

In my opinion, if you want to learn this sort of thing, you should do so in the order listed above. One thing that is extremely important, is that you do not rush into this. You seem very eager, and while that is a good thing, if you find yourself in too deep, you’ll run out of steam and drown in it. Take it one step at a time.
References :

Beginner’s HTML Tutorial: http://www.htmlbasix.com/
How to Create a Webpage: http://www.make-a-web-site.com/
Web Site Blog: http://www.instant-web-site-tools.com/blog/
http://www.w3schools.com/site/default.asp

http://www.thesitewizard.com/gettingstarted/startwebsite.shtml

Free Editors:

KompoZer: http://kompozer.net/
PageBreeze (both a visual and html source editor): http://www.pagebreeze.com/download.htm

Ron
References :