base directory of Xfce an installation of Orage 4.5

[Alessia Moretti]

Hello all,
I'm new of Xfce. I use Gnu/Linux since three - four years and I 've used 
mainly Mandriva distro and , sometime, *ubuntu and Suse,
almost always with KDE  enviroment.
Now I change to Xfce due an incompatibility between my old pc and the 
new KDE. I found Xfce very light and, after a little time, fully fitting 
to my needs.
Now I'd like to install the new Orage 4.5 with new features very 
interesting to me but I read this instructions in the Orage web site 
(section download) " unpack it to the same directory where your base 
Xfce is.". I'm not sure what doesn't mean exactly "base directory", 
because I usually install new package via rpm and urpmi so it' isn't 
clear to me where is the base directory of the applications. Searching 
with locate I've found some directories called Xfce like /usr/shareXfce 
or /usr/lib/Xfce.

But which of these is the "base directory"?

Excuse me for the quest, very dull for experts and maybe  connected with 
rpm package installation rather than Xfce

Thanks to all
Alessia