If you already have a SSL certificate but your site has insecure connection and still opens through http, do the following:

1. In the root folder > config.php > find the line starting with

define("SITE_SERVER"

2. Change http to https

3. In the .htaccess file (root directory), add redirect from http to https:

RewriteCond %{HTTPS} off
RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]