PHP Fusion on hosted site.....

[#1]

Ok, newbie install of PHP Fusion on a domain I'm hosting through Plusnet.
When I connect to the site, instead of getting the admin setup for PHP fusion, I'm getting a directory listing
Having looked on the PlusNet support, it mentions that I have to have any php in the CGI part of the site but this isn't under the domain name....?
Can I only install it to the CGI part and so is there no PHP support for my hosted domain?
Any help appreciated....
Thanks

[#2]

If say it is a forum it must go on the CGI Servers not the home pages Server.  php will not work on the home pages Server.