Setting up X in a gentoo install

[Alma J Wetzker]

I got an early present of an IBM T40 laptop.  So I installed gentoo.  I
compiled kde for it over the weekend.  When I type 'startx', I get some
other X manager that starts with three text windows.  I can't resize
them, and the bottoms go off the screen.  I can start kde within that
windows environment, but the results are less than satisfactory.  (It
does run fine.)  How and where do I change things so that xdm starts up
kde instead of what I am getting now?  I need baby steps here.  TIA

    -- Alma