JAVA_OPTS="${JAVA_OPTS} -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=8999 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false"
This specifies that no authentication is needed, which is fine in a test environment, but for a production environment, you would want to enable SSL and/or authentication (Google will find lots of links for you).
You do need to restart TBSM to have the changes take effect. Once it starts back up, you can view the JMX data using the jconsole command that is included with the Java 1.5 (and above) JDK. When you startup jconsole, specify the hostname of your TBSM server and port 8999 (specified above), with no user or password. That will give you a nifty GUI that looks like this:
One of the available tabs is "Memory", which will give you some (possibly) useful information about memory utilization in the JVM.
As you can see, there are other tabs, which you should investigate to see what additional information is available.