Need help with Post command

Hi - I need to write a java program to connect to a USPS REST API. I’m not a JAVA programmer, nor have I used Postman, so forgive my cluelessness.

Below is the USPS documentation for how to call the API.

*The epf/login function call is used to log into EPF system and retrieve the required keys for all future web service calls…

INPUT: Call the URL via POST method with JSON object serialized and set parameter.

obj={

login”:“[epf login required]”,

pword”:“[epf password required]”

My idea is to use Postman to connect, then I can cut and paste the generated JAVA code.

I’m not sure what “with JSON object serialized and set parameter”:

call the URL via POST method with JSON object serialized and set parameter.

In Postman, I’m trying to pass the ID and password via “Params”. I don’t even know if that’s right. When I run it, the error is “not authorized”. I know the ID/password are correct, since I can login to their web site with those credentials.(Although there could be some other permissions problem).

Anybody have a thought?

thanks