Authentication using API and add users

This answered my question and the problem is resolved.

https://jazz.net/wiki/bin/view/Main/DraftTeamProcessRestApi

Thanks everyone.

There are several examples in the 'snippets' folder of the Plain Client Libraries

e.g.
public class Snippet1 {

    private static String REPOSITORY_ADDRESS = System.getProperty("repositoryAddress", "https://localhost:9443/jazz");
    private static String USER_AND_PASSWORD = System.getProperty("snippetUserAndPassword", "test");
   
    public static void main(String[] args) {
        TeamPlatform.startup();
        try {    
            IProgressMonitor monitor = new SysoutProgressMonitor();
            login(monitor);
        } catch (TeamRepositoryException e) {
            System.out.println("Unable to login: " + e.getMessage());
        } finally {
            TeamPlatform.shutdown();
        }
    }

You can download the appropriate version under the "All Downloads" tab.

See com.ibm.rqm.url.client.RQMUrlUtlyLogin.login(String, String, String) in the RQM URL Utility (same version as your RQM server) source (https://jazz.net/wiki/bin/view/Main/RQMURLUtility#Accessing_the_Source) for the required HTTP requests to authenticate with the JTS server.