You can put this code into your .htaccess file in the root of the site:
Code:
RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]
This will tell any browser that hits your site on port 80 (http) to use https instead and that the redirection is permanent (301) vs temporary (302).
Note that if you already have rewrites don't turn RewriteEngine On multiple times.
