Trying to get output from Postman

Your question may already have an answer on the community forum. Please search for related topics, and then read through the guidelines before creating a new topic.

Here’s an outline with best practices for making your inquiry.

My question:
I am new to REST API.
I have got these information and trying to use Postman to pull details.

This is document regards to API:

First of all, I am not sure what the Step 1 is.

Bottom is screenshot from this URL:

Details (like screenshots):

Am I on the right track?

Thanks for help.

How I found the problem:

I’ve already tried: