Configuring Sharepoint in private network for public access

I am new to Sharepoint and am trying to setup Sharepoint on a server which resides in a private network.  Some of the content of the site will be highly sensitive so we really don't want to expose the server to the public.  However, there are some users which don't have direct access to our network that need to access content that is not sensitive.  I have been searching for a solution which would allow us to keep the server private but allow a select group of users the ability to access the relevant content on the Sharepoint site.  Ideally this solution would not require things like a VPN client.  If anyone has any ideas on how to address this issue it would be much appreciated.