Within HTML you use tags to define how text, pictures, and other objects should appear in a Web browser. The topics within Working with HTML discuss many of the tags you can use to create Web pages. You use most tags in pairs - a start and ending tag. You can visit various web sites that explain HTML and how to use it.
Go to the NCSA Beginner's guide to HTML.
OR
Go to Getting started with HTML from W3C by Dave Raggett.