If you are trying to develop new website for your domain and want to redirect all the queries from internet to old directory, the just copy below code and put it at the beginning of .htaccess file and upload to root directory of your domain using ftp.
RewriteEngine on
RewriteBase /
RewriteCond %{REQUEST_URI} !^/old/
# Rewrites all URLS [Replace "domain" with the actual domain, without the TLD (.com, .net, .biz, etc)]
RewriteCond %{HTTP_HOST} ^(www\.)?yourdomain\.
# Rewrite all those to insert /folder
RewriteRule ^(.*)$ /old/$1 [L]Above code will redirect all queries from your website’s urls from search engine to old website with same link.
Now if you want to exclude some URL’s from the redirect, check the post