Creating a user using the Duo Security Admin API

Question

Following the documentation for the Duo Security Admin API, I am trying to create/delete a user. The documentation only indicates that a post command needs to be used. No examples are given and I’m not sure where to start.

I am trying to create a user and also delete a user using the following code. Neither works as I am not seeing the user being created or deleted in my admin console.

{"code": 40101, "message": "Missing request credentials", "stat": "FAIL"}

When I paste my URL I get this error and user is not created. What am I doing wrong?

import java.io.*;
import java.net.URL;
import java.net.HttpURLConnection;

public class duo {
    public static void main(String[] args) throws IOException, InterruptedException {
        // Create a neat value object to hold the URL
        URL url;
        url = new URL("https://api-e9770554.duosecurity.com/admin/v1/users");

        // Open a connection(?) on the URL(??) and cast the response(???)
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        // Now it's "open", we can set the request method, headers etc.
        connection.setRequestProperty("accept", "application/json");

        // This line makes the request
        InputStream responseStream = connection.getInputStream();
    }
}