You'll note that although the site appears to work in FireFox the url doesn't change - the default.html stays in the browser's address bar.
You've authored the site in MS Word, and although you've made a pretty good job of it to be honest that's at the root of the problem. To save taking up a mass of space here I suggest that you
click here and enter the url of your default page. When the results appear you'll see what I mean.
Have you considered using one of the popular WYSIWYG web-design programs, like NetObjects Fusion, or Microsoft FrontPage? I think you would find things a whole lot easier if you did, and we'll provide as much help and advice as you need.