You can launch Mozart with the command /usr/local/mozart/bin/oz.
An Emacs window should open, the top buffer is for writing a program,
the bottom buffer, shows output from the Oz compiler.
As a quick test, write the program:
{Browse 1 + 2}
Move your cursor to that line, and ``feed the line'' (Open
Oz-menu, and you can see the key-binding C-. C-l for that command).
A separate window ``Oz Browser'' should appear, and show the result.
For further information on using Mozart and Oz, read the relevant section in
the book, and Mozart documentation.