How can I use XFCE to instead GNOME

[Mike Zang]

I am running a web server(FC4) on an old laptop, I found it is very slow if
I use GNOME, I heard XFCE is light and better to use in my case.

At the moment, my server is running in terminal mode, that is no problem. I
use in GNOME by VNC SERVER, now I want to change to XFCE, I tried, but not
successful, because I don't know how config for VNC, 

Does anyone help me in detail? I am new for XFCE and VNC.