$HOME/.Xdefaults
if you don't want a color then
XTerm*colorMode: off
or you can start xterm -cm then it's mono
you can choose between 16 RGB color types all explained in man pages.
to test it you can issue the command:
xrdb -merge $HOME/.Xdefaults
for e.g. color 3 as darkred would be
XTerm*color3: darkred
you also can use the xtermset-Homepage from
here
then you could for e.g. set a blinking red coursor like this
xtermset tc Red
and also use another title like this
xtermset title "Linux rocks"
and with xtermset bg you would change the backgroud.
hope you'll be happy then :-)