This should have been its own topic, as it doesn’t seem related to the original question.
This type of activity is covered in the Postman Learning Centre.
If you are new to Postman, then I would suggest a visit to the Learning Centre.
Overview | Postman Learning Center
Including the Postman Training links under “Other Resources”.
I would recommend the “Galaxy APIs 101” course first as it gets you used to the application features.
Then the “Galaxy Testing and Automation” course which teaches you how to assert the responses. It includes basic scripting.