Before you launch the deployed application, you need to start the instances in the cluster.
In the tree on the left pane, click Clusters, and click the cluster1 node.
In the right pane, navigate to the General tab if it is not already active.
If the instances are not already running, the Start Instances button is active. Click it to start the cluster's instances.
Verify that they have started by checking the Status field, which indicates how many instances are running.
You are now ready to launch the application. See To Start the Instances in a Cluster
You can start instances by using the asadmin start-intance command. See in the Sun Java System Application Server 9.1 Reference Manual.