Is your website made using iWeb?
If not you need to put all the websites files in to the "www" directory and make sure the page you are using as the landing page is called index.xxx Where .xxx it should be either .html OR .php
This may require you to make some changes to the code if you're renaming a page like home.html to index.html
The second option is to redirect the user to the relevant page with an index.html file. Here below is the code I like to use to do this.
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"><head><title></title><meta http-equiv="refresh" content="0;url= http://example.com/site/home.html" />