To configure JMS, the JMS Resources portlet is available on the Geronimo Administration Console. Select the link Services > JMS Resources. From this portlet you can not only list available resources but also create new ones for ActiveMQ already available in Geronimo or for another JMS provider.
The portlet lists the ActiveMQ resource adapters which can be of type Connection Factory or Queue. To create a new JMS resource group click on the For ActiveMQ or For another JMS provider... links.