Hover over Appearances and click on Customize.
The customize page, just like the preview page, allows you to change many features of your site, depending, on the theme. Some of these include:
Site Title & Tagline, for describing your site
Widgets, for added functionality and display in various parts of your site
Static Front Page, which is used to set the homepage of your site to a page you’re created where necessary.
Note that different themes have different options on the customize screen.