xfce4 - xfwm4 start ? How ?

[Uwe Dippel <udippel@uniten.edu.my>]

Regular user of xfce (3.8).
Now installed all xfce4-packages on Sarge.
How to start ? (with kdm)

xfce starts with xfwm from kdm.
xfwm4 shows up on kdm, but starting it ends in nirwana: some
harddisk-activity and that's it. Have to issue Ctrl-Alt-Backspace to get
out of that nothing.

I did follow an earlier post and created an ~/.xsession. This starts as
default, but very limited: no mouse action but click, no background
configuration (kdm background remains).

There is no startxfce4 (google says that's the one to use).

in the README it says one should use xfce4-session, but on terminal it
will tell me: 'Cannot open display' and from an xfwm4-session it will
simply do the same as the .xsession: Only some applets in the
configuration application.

xfmw4 from terminal also 'cannot open display'.

Now I'm lost.