Under Unix, the graphical environment system is "X-Windows". X-Windows provides a very, very, basic environment. Basically, just the ability to have windows appear, not even the ability to move them around. You have to run an additional piece of software on top of X-Windows to provide an actual user interface. There are many different ones of these, KDE being one. By running "startkde" directly, you're trying to get it to provide a GUI on top of an X-Windows instance that doesn't exist. Usually, startkde is run automatically, not by hand.

At this point, it sounds like you've missed some configuration of your system. Chances are that it will start up in a GUI environment when you configure it properly. Unfortunately, I'm not immediately familiar enough with Suse to tell you how to do that.