Well there are many tutorials on the internet.. So I am going to give you a couple of pointers that should help you get started..
A web page has 4 basic parts:
1. Content [Text/Media..] :
Content is added into the page using HTML tags. So HTML helps define the page content [like using header tags for article headers and paragraph tags for paragraphs]. HTML acts as the foundation of any webpage and so this is where you should start! :)
Reference: http://www.w3schools.com/html/ - this is an AWESOME site! Covers all the basics and whenever I go back to it I keep learning new stuff!
2. Presentation/Layout:
CSS styles allow you to define the "look" of your page. Remember to always use HTML only to add content to the page and not to define the look/layout of the page. Eg. Never use table tags [HTML tag] to define the page layout, use table only to display tabular data. You need to study how to create CSS layouts [CSS Box model]..
http://www.w3schools.com/css/default.asp
3. Front-end functionality:
Here is where Javascript/JS comes in. Once you are familiar with the capabilities of JS, you can start studying JQuery which is the best JS framework out there.. It makes it super easy to do amazing JS stuff.. like cool animations, AJAX [loading content dynamically.. like the popup you see when you move your mouse over a persons avatar] and so on..
4. Back-end functionality:
This is a whole different domain all together. there's lots to learn here. This part deals with loading content from the database onto the pages in front [eg. loading this answer from the database onto this page!] and storing the data submitted from front end forms or user interactions into the database..
Well its best to first concentrate on design and get all your basics right.. Once you are clear how the front end works, you can then concentrate on the studying the backend technologies [PHP, MySQL..]. This will enable you to best design web applications that requires a person to understand the capabilities of the front end JS and backend programming..
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So as part of design, you could continue using dreamweaver, but also try free tools like netbeans.
You MUST design all your sites in Mozilla Firefox [which correctly follows all the W3C standards] and then work towards cross-browser compatibility!
***IMP***: Use the free firebug add-on in firefox to understand and design sites faster!
All the best!