There are two ways in which you can activate your website.
1. While on the Free Plan, simply enter a subdomain on the Site Address and Content Page.
2. While on a paid subscription, ensure that you've indicated your preferred domain name on the Site Address and Content Page
After you website is live, you can change any of the settings that control what appears on your website and how it appears on your website. In other words, no settings are locked following the activation of your website.