See here for a more general description of HTML.
And here is an overview of URL's (Universal Resource Locators) -- the links that make hypertext "hyper".
Finally, here is a style guide for Hypertext documents -- it provides some pointers on what to think about while writing. (Many thanks to Tony Sanders for his comments and pointing these references out!)
Also we have a little bit of help for setting up Xmosaic, the most common browser at the IU CS department (see here for a general description of Xmosaic).