As you can see, this screen allows you to pick a new Theme. But you can also customize options that affect the Entire Page, the Site Header area, the Content Area, Content Area Gadgets, Sidebar Gadgets, and the Horizontal Navigation. In each of these sections, there are multiple options to choose from, too many to full list out in detail here. Suffice it to say, there are enough options for you to fully customize and personalize your site to your tastes.