My advice is to learn the basics first...Internet is a great resource, so you won't have any problems finding an appropriate read. But, the best way to learn something is practice. At first, I used Dreamweaver, only the WYSIWYG part of it. After a while, I was starting to get more interest in code...so I examined the code more closely. As you were suggested, try to edit already made templates or websites. Once you become familiar with the html/CSS structure, go one step further and open blank notepad file and write. It will be a little tough at the beginning, but If you are persistent it won't be long until you are able to make website by using only notepad or similar text editor (I suggest and use notepad2 for syntax highlighting, it helps a lot).
you can learned css by the editing the source code, using that code you can easily learn about CSS and HTML. copy that code & paste it into the Dreamweaver, go into the design and use the structure of the website. You can edit it and use it, editing the parts of the code. It is the useful way to learn the CSS and HTML.
I can edit PHP, HTML, CSS code, but starting from a blank page is another story completely, i'm more of a designer anyway photoshop is my specialty.
I learned it just by playong around with mt first website, i have never read online how to do it with css...maybe a few times but yeah here is my site http://www.otzwire.com
Lots of google, lots of online tutorials, painful trial and lots of error! And am still no more than a blundering novice!
I tried playing around with a few things but for whatever reason one day the whole process just 'clicked' for me and it all fell into place. Since then I've been pretty fluent at it, teaching myself through trial and error. Sometimes I used to offer the css on top of my design service for free to practice.
w3schools is a really great resource. If you want to edit the html online then I recommend easywebcontent.com
I learned css by downloading a free template and messing up with the css file. Changing stuff there and then refreshing the template and see what the changes did. Over and over and over and over again. When I had studied long enough I made my first template, which was a crappy...but first. Then I made some more templates and googled for advice and many many times asked here for advice.
Read a really good book from Head First Labs appropriately titled "HTML with CSS & XHTML". Their style of teaching makes it real easy to learn. Google them and you can either get a hardcopy or an ebook version, well worth it.