RewriteEngine on
RewriteBase /

#enforce www subdomain
RewriteCond %{HTTP_HOST} !^$
RewriteCond %{HTTP_HOST} ^sitename.com [NC]
RewriteCond %{HTTPS}s ^on(s)|
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

RewriteRule  new/admin  -  [S=2]
RewriteRule  ^$ new/    [L]
RewriteRule  (.*) new/$1 [L]


  [1]: https://i.stack.imgur.com/ISPR0.png