Can anyone point me where I can get a basic introduction to the functionality of TestDirector

I am familiar with Rational's TestManager however I need to compare it with TestDirector. Basically these are some of the answers I need
- What's the test plan hierarchy in TD? In TM this is as follows
Project -> Test Plan -> Test case Folder -> Test case -> test script
- Can you attach test scripts to a test case
- What's is the easiest way to write a test plan in TD etc. etc.

I have managed to find a Winrunner user guide but I can't find anything specific on TD. Even a white paper which describes it's essential functionality will help me.

If anyone can help it's much appreciated.