To forward a website to use both www. and https:// use the following in an .htaccess file:
RewriteCond %{HTTPS} off
RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule .* https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
If that code doesn't work please try the following...
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*) https://www.%{SERVER_NAME}%{REQUEST_URI} [L,R=301]
RewriteCond %{HTTPS} off
RewriteRule ^(.*) https://%{SERVER_NAME}%{REQUEST_URI} [L,R=301]