When you are going to sever all requests over SSL then in some cases you need to only serve requests over SSL. While doing that you may have to disable port 80 so that all the requests will be only served through SSL. But in that case if user hits your url with http, user will see page not found error. Instead you can enable your port 80 and redirect all requests to https url with following configuration.
server {
listen 80;
server_name www.yourdomain.com;
return 301 https://www.yourdomain.com$request_uri;
}
Adding $request_uri will make sure it will keep requested url as is as per requested. Other wise even if you hit the url like http://www.yourdomain.com/company/about.html still it will be redirected to https://www.yourdomain.com