Using your existing JMSAdmin configuration
If you have used JMSAdmin before, then it is assumed that you are familiar with editing your 'jmsadmin.config' file and have used that to connect to a JNDI repository.
This tool can read the JMSAdmin config files and so by selecting 'Open' from the file menu, select the existing JMSAdmin config file which is probably located in you <WMQ Install Directory>/Java/bin directory.
When the file is loaded, connection to that repository should occur automatically. Once connected you can modify your connection settings or create and administer objects.