How do I configure the Services OAuth sub-module?
There is a handbook page covering testing Oauth based services at http://drupal.org/node/942866 . This does assume that you have some familiarity with both oauth and the drupal oauth module.

The basic workflow as far as implementation goes is:


Set up an oauth context.
Set your service to use oauth authorisation
Configure the authorisation for all your resource operations.
Configure one or more oauth consumers


For testing you're probably going to have to write your own client code which generates the oauth signature and then passes that with your service requests.

For learning more about Oauth itself I recommend you start by reading this guide which is fairly comprehensive - 
http://hueniverse.com/2007/10/beginners-guide-to-oauth-part-i-overview/