One of the best things to do is find some simplistic pages and view the code. Use an html tag reference (google one, there's plenty out there) and analyze how the page is put together; how what you see as code translates to what is displayed on a page. That will give you a quick grasp of html elements and their use.
Most sites will use CSS to style the elements, and if the page you're looking at specifies a stylesheet, look in your internet cache for the corresponding file. View that, with the help of a CSS reference, and you'll see how everything comes together to create the page.
That's really the basics of it. Creating web pages really isn't that difficult at all. When you get to making your own page, one thing that may help is to create a mock up of the page in something like Photoshop first, and then use that as your visual guide when trying to determine the best approach to coding the page.