Please help newbie!! -'Undefined reference'

[Dave <dave at lara dot com>]

Hello all,
this isn't really a qt question.  However, last week, I downloaded and
installed the
free qt, 2.0.2 I think it is.  (I have a mandrake linux system with
KDE).  I was able
to get qt to compile just fine, and all of the example apps work fine,
but when I try to
g++ or gcc any of the tutorial programs, I get a slew of 'undefined
reference' errors.
I have checked the qt docs, and they list this problem in one of their
faqs, and suggest
that the problem might be resolved by removing the old qt library.
However, I am
nervous about doing this, because I have heard that some KDE apps are
dependant
upon older library functions.  I have the proper $QTDIR in my
environment variables,
and my $PATH and etc. seems to be fine, but gcc is still not finding
it.  I also have the
proper path listed in the /etc/ld.so.conf file whose function I have no
real
comprehension of, but I feel it is somehow connected (it's kind of a
mystical feeling...).

My real question: can someone tell me, where do I find the place, file,
command,
function, whatever...that tells gcc/g++ where to find the proper include
files for this
library?  How can I make sure that it is not getting confused?  In the
qt docs, it was
hinted that this is possible, but no mention is made as to how.  If that
fails, is there
any standard way to remove all of the old qt files, any standard
directories that
libraries get placed (is it /usr/include?), and how can I ensure that
everything is gone?

As an aside, where can I find out some good contextual information on
ldconfig and
ld.so.conf and what the hell they actually do?  I have a feeling that my
question and
these are connected.  And if one would point me towards documentation
rather than
answer my questions, that's fine, I would love to RTFM, I just have no
clue which
FM to read.

Thanks much,
-Dave DellaCosta