hackdaddy,
After reading TFM myself, I would have phrased your question this way:

TFM says that the fe elements must be children of the Filter element, but they don't have any explanation of how to do that. I know what I want to get to, but I have know idea how to write the code. Anyone know of better docs or can provide an example?

When I can't figure something out from the docs, I tend to check the test suite to see if they have an example. In this case you are in luck - see 18-filter.pl from the test suite.