So you would need to create the following server directives in your nginx configuration:

To redirect HTTP to HTTPS you can use the following:

server {
    listen 80;

    server_name domain.com;
    return 301 https://www.domain.com$request_uri;
}

To redirect an HTTPS request from domain.com to www.domain.com you can also add the following

server {
    listen 443;

    server_name domain.com;
    return 301 https://www.domain.com$request_uri;
}

Then just add your regular SSL HTTPS configuration for your site in another server directive and you will be all set.