FYI - you do have to install
FXFactory first, before you can load & use the plugin. FxFactory is also free.
There are loads of plugins for Final Cut Express, some free, some have a price. There's no one place you can find them all. If you search on the web (or even in this forum) you will find various lists & recommendations. (Hmmm ... maybe I should put such a list together ...)
I particularly like Patrick Sheffield's
Technicolor plugins (free) and Graeme Nattress'
Film Effects and
Big Box of Tricks
There are many film and video forums and a number of FCE forums (eg dvcreators, 2-pop, videomaker, etc.) - but imho the one you are in right now is by far the best of the lot. Also, if you search you will find a number of FCPro forums ... and there is a good one right in Sydney - the
SydneyFCP ! Take a look!