I have to say that whatever anyone’s reservations about FCPX the one thing you cannot fault it on is the ability to organize your media in ways you hadn’t even imagined possible. Hard to know where to start on your question, but try selecting a range and applying a keyword and hopefully you’ll start to get it.
The great thing is that you can easily organize the same footage in different ways (different keywords and so forth) which is a genuinely intruiging new development for a lot of users.
Totally agree with Simon. The strides made in organization are incredibly long over due in NLEs. I mean, I’ve been able to so this with photos for so long. And if you want to get real giddy, check the amount of available metadata for each clip. So many possibilities for the future, especially if I were a plugin maker. I also see this getting some of the features Final Cut Server has, sorry, had… so you have one program to do all your organizational stuff instead of two mostly disconnected ones.
As for you question, check out the Keyword section in the manual. Should get you up to speed in no time.