Cisco ISE API/Fetch a Group ID

Folks, we are beginning the journey to work on API's with the Cisco ISE. Honestly, I am a novice to know anything about API's.

The first tasks is to write a API to fetch the Identity Groups in the Cisco ISE.

Here is the documentation we were able to find: https://developer.cisco.com/docs/identity-services-engine/latest/#!endpointgroup

However, how to start with the API?

I got Postman installed to test this out and unable to find the correct XML/JSON for this.

Any help?

Thanks, Nik.