First off, /var/www/html/ is most likely the document root directory defined to your Web Server. That means that http://example.com will look to documents in the /var/www/html/ for rendering.
It also looks like you may be uploading your home page to a directory path /var/www/html/, which is ultimately http://example.com/var/www/html/ from a browser and /var/www/html/var/www/html/ on the server.
I think you will be good to go if you upload your home page to the base directory you FTP into without the /var/www/html/.
Also, in order to edit the httpd.conf file, you will need root level access to your server. Contact your HSP to see if you have higher level access rights to your server and how you can get to that file and other configuration files below your document root path. Unless you have a control panel or some other interface tool, PuTTY is the SSH tool I use for editing my config files on my server.
If the HSP does not allow you access to lower paths, then they might make the configuration changes for you, if you give them specific direction and content.