Redirect all non-HTTPS traffic to HTTPS using htaccess
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTPS} !on [NC]
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]
</IfModule>
for more htaccess tips, go to this url:
https://www.leaseweb.com/labs/tag/htaccess/
