The standard for naming a home page is index.html (or index.htm, default.html, or index.php).
I would simply suggest you name your home page index.html and go through all your other pages to change the link to your home page to reflect the change. If you have a bunch of pages, you might want to think about using some sort of include code on all your pages. Making your menu system its own file and including it in all your other pages will drastically cut down on your update time if you have to add or take away a page.
I'm not familiar with iWeb, but all websites are built with html. There might be other languages that make up the core of the site, like php, asp, coldfusion and others, but all these languages and technologies always output html to the browser window.
You might also be able to get away with not changing your links if you know a bit of .htaccess code to make the browser look for home.html instead of index.html, but I still think your best bet would be to change the links to your home page.
If you want to do this directly inside the html code, look for tags that look similar to this:
HTML Code:
<a href="home.html">Home</a>
And change it to something similar to this:
HTML Code:
<a href="index.html">Home</a>
~regards