Post request for Rest API

How to test Post request for API. Here I have found the tutorial Create REST API Requests Manually With Katalon Studio - DZone DevOps but not able to placed the code. I mean where I place the code in, Object repository, test case or where? Please guide

@nazneen
Please use this video tutorial for REST API Testing
https://docs.katalon.com/katalon-studio/videos/rest-api-testing.html