Welcome to Dreamhost! Your "site" looks the way it does because you have yet to load any "webpages" into your site space. The whole subject of how to create "pages" and make them into a site is a huge subject; you can spend years (and many of us have!) learning the appropriate web technologies to produce websites (html, xhtml, css, scripting languages, graphics manipulation, etc.)
That said, everyone has to start somewhere, so I suggest some exploration of the DH wiki Article on "Building Web Pages".
If you read this article, one of the first things you should notice is the suggestion that you don't even have to "build it from scratch" yourself, as DH offers several content creation tools to help you with all this as "one-click" installations. These programs allow you to "get right to it" and get pages online very quickly with the bare minimum of web production knowledge. Many never progress beyond the use of these tools, as they find their needs are adequately addressed in this way.
Of these tools, I suggest that a WordPress installation provides great flexibility in what and how you put pages online, and is probably the easiest to use "out of the box".
Dive in in and experiment (you can always start over if you don't like what you have done!). Unless you are striving to become a "serious" web developer, go build your first WordPress based site using the "one-click" installer, and start having fun!