HTTP POST REQUEST with Postman

I am learning Express JS and sending HTTP POST requests using Postman. When I send a request, and it is successful(status code: 200) via Postman, is the database in my server updated? I know Mosh’s video mentions Postman ‘tests’ the endpoint request. But how do I actually update the data on my server (ex. localhost:3000/API/database)?

I tried to make a Get request to my localhost but my database did not get updated with the Post request via Postman. Any clarification would be appreciated! Thanks.