Migrate a site from Sitebuilder to the Online Website Builder?

We received an email stating our current site will be flagged by Google as unsecure because it does not have HTTPS enabled with a SSL certificate.  The email states we can get a free SSL certificate by "moving over to the online Website Builder product".  How do we do this?  There are no instructions included, can't find anything on the Homestead site, can't find anything when we log into the account.

I've also seen posts of people building more than one site within their account and switching the domain over to the other site but I don't see where I can create multiple websites within my account.

We may actually like the online builder better but don't know.  The old SiteBuilder is a PITA.  Need help.