Just click on the ‘Preview’ link. This option allows you to Preview your website to see exactly how it would appear before publishing it to the live server. You can preview your website at any time during your site building process to immediately check and see how your recent changes will be reflected on your final website. The Preview opens in a new window so you can always continue working with the Website Manager without disturbing your flow.
[Note: What you see in a Preview is still not part of your live website. You will need to Publish it to make it live for your visitors to see the changes.]
Check the following tutorial for step by step instructions – How to Build a Website with Website Builder