Can I use my own domain?
Yes, and we encourage you to do so!
When you create your site, it will first have a URL like
http://myschool.simplwebsite.com
You can work on your site at that URL. People and Google won't know about it unless you give them the url.
When you are ready to "go live", you need to register a domain (we recommend GoDaddy) and create two A records to our server.
http://support.simplweb.com/help/kb/setting-up-your-website/how-do-...