TestLink

Hi all,
is there somebody who can give me a short introduction into the TestLink XMLRPC operation mode? I try to run the python example from API documentation, but can't bring it to work even though i read a lot of posts in this forum.

There are some beginner questions like:
What is the general communication model?
How to setup the TestLink XMLRPC server?
How to start the TestLink XMLRPC server?
Do i need to configure a server port? If yes, where?
Do i need to specify custom fields like "tc_server_host", "tc_server_port", "tc_server_path" to run the server?

I would be glad for any advice.

Thanks in advance