Using .htaccess you can do many things. This small tidbit will focus on removing and rewriting (mask, hide) the subfolder aspect on a URL to only have the base domain present. You will want to create a .htaccess file if one is not present already in your public_html (or main doc root) for the site.
Yes I like nano! got something with it? Ha. Use whatever you like such as VIM if you prefer. Next you will add the following text to the file.
RewriteEngine On
RewriteRule ^$ sub/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ sub/$1
This will assume you have http://domain.com/sub as where the content you want to load is. And the resulting URL to only show http://domain.com but still load the content in in the /sub folder. This could be modified many ways to suit the needs for the application at hand.