edit your .htacess and put a line like this:
DirectoryIndex other_index.html
where 'other_index.html' is the name of the file you want as your starting page. The downside is that this affects every subdirectory too. For example, my first page was named 'main.html' and the server expected it to be index.html. My .htaccess file was edited to say:
DirectoryIndex main.html
and that worked great, until someone went to www.mysite.com/subdirectory. In that subdirectory, the server would not recognize index.html as the main page. It was looking for main.html as specified in my .htaccess file. So, what you do is add a 2nd option in there, like:
DirectoryIndex main.html index.html
Meaning the server first looks for main.html, and if that's not found it looks for index.html. You can also add other entries too. I've not tried, but I assume that if you wanted www.yersite.com/blog/index.html as your starting page, you could do something like:
DirectoryIndex blog\index.html
But you might have to mess with the syntax to get it right (\blog\index.html or .\blog\index.html, etc)