adding gdm sessions

[komplikazione <komplikazione yahoo it>]

hi 

i'm trying to add a fvwm-theme-start in gdm session, but i can't find a way to 
do that. In the readme thet are talking about a file .xsession that should be 
in $HOME but i haven't.

Actually i can choose gnome , kde  and fvwm, but i need to change fvwm with 
fvwm-themes-start.

I hope you can help me

bye