type
 
startx
 
to start the X server. To make Debian boot into X by default, edit
 
/etc/inittab
 
and change init 3 to init 5

i alredy did dat but its not working. im runnning debian using colinux.

With colinux, it is a bit more complicated to run a gui with debian. Per default, it isn't installed. So, you have to first install kde and some other packages. A guide to this installation can be found her http://wiki.colinux.org/cgi-bin/coLinuxASAP.
 
Note, that it is especally important not to reboot Debian after the installation. First, you have to override the default display manager with this command:
echo "null" > /etc/X11/default-display-manager
 
Perhaps it would also be a good idea to make a backup of the debian-image-file before the installation of kde.