Oracle Database Discussions

I'm a grad student using Oracle 10g for a database class. I successfully installed Oracle 10g on Mac OS X Snow Leopard and can use SQL Developer. However, I can't access Enterprise Manager at all. Any attempt to visit https://localhost:1158/em returns "Unable to Connect: Firefox can't establish a connection to the server at localhost:1158." message. I've read conflicting things on the net -- some saying Enterprise Manager will run, others saying it won't on Mac.

Since I'm new to DBMS, I'm not sure quite what to ask.

1) If EM can run on a Mac, what must I do to make it so? (Detailed steps are important.)

2) If EM won't run on a Mac, what alternatives do I have for creating new databases, namespaces, etc. and other functions of Enterprise Manager?

Thanks.