as I remember, by default your sites are stored in.. let it be /var/www/html.
so file /var/www/html/index.htm is available from http://localhost
if you want to create virtual folder - just create subfolder in /var/www/html: /var/www/html/site1
so file /var/www/html/site1/index.htm is available from http://localhost/site1
you may use 'ln -s', if you want to store sites in your home directory.