Does anybody have an example of setting up Postman to do API calls to Constant Contact?

Hi there, I'm trying to do something simple...set up Postman to do simple API calls so that I can explore the Constant Contact API and prep our actual backend engineers to be able to build a cool integration. I'm personally not an Oauth2 expert, so I need some simple instructions to be able to make this work. I've done a bunch of searching but none of the solutions seem to work for me (or I just don't know enough to do it correctly).

Thanks, Neil