Tumblr users see the blogs that they subscribe to, as well their own posts and notes, on the Dashboard interface. But the public "face" of a Tumblr blog goes out to the whole of the Internet (unless privacy features are enabled), which means that they require some cosmetic maintenance. Users can fully customize their Tumblr sites, changing the colors and fonts, how pictures are displays, where modules are presented, and so on. Tumblr makes it easy for the non-computer coder to do so by offering dozens of free site templates, which it calls "Themes."
Here's how you set up a theme. First, go to your site's page on the Dashboard. Then, open the "customize theme" module. Tumblr provides a pull-down theme menu, with thumbnail images of themes currently available, many designed by other Tumblr users. Based on what you'll be using your Tumblr for, there are several theme options available. A blogger can choose from single, double or triple column (for a text-heavy, photo-light newspaper layout), or high-resolution (for a photo-dominant blog), for example. Most themes are free, although Tumblr does sell "premium" themes.
Once you find a theme you like, you can install it with the push of a button. With a dummy example page, you're then free to explore the customizable features. From this page, you can change the background color (or pattern, or an uploaded image), entry text size and color, the site's title and description, and even how many older entries you want displayed your page. (It also allows for user-generated code injection.) You can fiddle with anything here. Beyond the click-and-make-it-happen interface, all themes and all customizable features can also be altered with HTML editing, for the more code-savvy blogger or blogger who wants a very specific look out of his or her page.
One more thing you can put on your Tumblr page: music. Read on to see how.