if your jvm works with your browser then you're at your console:
this router is running in your browser without real interfaces.
it connects to the demo server and brings up bgp with it.
this demo server also connected to dn42
so you will see dn42 routes in your browser.
if you have no jvm in your browser then download
rtr.jar and online-sw.txt
and start with "java -jar rtr.jar routerc online-" to get connected.
to get a nice console, try "test window" command.