From the Site Center:
- Click the Tools tab.
- Click the Select button for Homepage Templates.
- Select the desired template from the list of options by clicking on the template name.
- Click the Select button.
The preview pane to the right of the list of templates has icons for mobile, tablet, and desktop views. You may also click the PREVIEW link to view the template in another tab.
You can also view live examples of the templates. Switch with the menu at the upper right.