GMT Panzer Exp modules question

Hello, I am not expert at VASSAL as I am a infrequent gamer anymore. Anyway, I’d like to start playing GMT’s Panzer and it’s expansion sets. I downloaded the main Panzer game and it works fine. I downloaded both Panzer expansions and can’t get either to work. I am sure I am overlooking something. something simple. If someone could point me in the right direction, I would appreciate it very much.
Thanks,
Chuck

in the module manager right click on the Panzer module and select “add extension” to load the extensions in…browse to your extension file rinse/repeat as necessary