Weebly on Fatcow - Need to temporarily hide the nav bar or say 'Under Construction' - repost

I have a Weebly website on Fatcow. I don't want the public to see any content on the index page and so I need the nav bar to not show, and/or display an 'under construction' message. Later on I'll be ready to release the website to the public, but for now I am not clever enough to know how to make the nav bar stop showing (and the techs at Fatcow aren't seemingly able to help me with good advice). All the other pages aside from the index page will need to continue to be visible to any browser on the web. This is so I can see the work I am publishing as I go along adding content. I bet this is a 5 minute fix for someone out there who can instruct me on how to accomplish an 'under construction' message, or at least help me figure out how to make the nav bar stop showing on the index page. I'm guessing it would be beneficialy to understand Fatcow's environment to accomplish this job. Thanks Dave I will also need to be told how to make it again show when I launch the website in October.