Currently you can only connect one domain to your Breezi site by pointing your domain. If need be you can set up forwards (a.k.a. redirects) from other domains to the domain you’ve connected with your Breezi site – this can be done through your service provider you registered your domain through or wherever you can manage DNS settings.
However, if you need a separate website, with it’s own content, design, pages, etc. and you’ll be using a different domain than the one you already have connected to your Breezi site, you’ll just need to create another Breezi account for the new site.