Make sure that you've started the Web
server.
Configure your Firefox 3 as follows:
Both of these are extremely important. Popups must be unblocked in
order to view errors and other notifications in the UI, and the file
save dialog allows you to modify the names of the annotated files you
save.
Once the Web server is started and Firefox is configured, you can navigate to http://localhost:7801/MAT/desktop to start up the UI.