I've this code during my .htaccess file as proven below.....

RewriteEngine On
RewriteCond %{HTTPS} off RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI}

It was put into redirect http to https.....therefore the entire website is now in https version.

Now I wish to redirect from non-www to www. After i type mydomain.com i ought to be rerouted to https://www.mydomain.com/

How do you do this with htaccess file?

Place the following lines directly into your .htaccess file and replace mydomain.com using the domain that you would like to redirect.

RewriteEngine On
RewriteCond %{HTTP_HOST} ^(www\.){0,1}mydomain.com$ [OR]
RewriteCond %{HTTPS_HOST} ^(www\.){0,1}mydomain.com$
RewriteRule ^(.*)$ https://www.mydomain.com/$1 [R=301,L]

With this to operate you'll have to take away the existing records that you simply mention inside your question in the .htaccess file