Please help me !! (pkg-config)

Hi everybody!!

I'm a Mac OS X user who loves using Darwin UNIX, although I'm a beginner in these things.
I've used several Linux versions and now I'm working on Darwin.

My problem is this:
Everytime I try to install something at Darwin, I get the same problem: "you don't have pkg-config".
I've downloaded it but I DO NOT KNOW HOW TO INSTALL IT !! hehehe

I type the typical:
"./configure"
and then
"make"
but I always get the same error:

/bin/sh ./libtool --mode=compile gcc -DHAVE_CONFIG_H -I. -I. -I. -DG_LOG_DOMAIN=g_log_domain_glib -g -O2 -Wall -D_REENTRANT -c giounix.c
gcc -DHAVE_CONFIG_H -I. -I. -I. -DG_LOG_DOMAIN=g_log_domain_glib -g -O2 -Wall -D_REENTRANT -c giounix.c -o giounix.o
giounix.c:233: only 1 arg to macro 'g_warning' (2 expected)
cpp-precomp: warning: errors during smart preprocessing, retrying in basic mode
make[4]: *** [giounix.lo] Error 1
make[3]: *** [all-recursive] Error 1
make[2]: *** [all-recursive-am] Error 2
make[1]: *** [all-recursive] Error 1
make: *** [all-recursive-am] Error 2

does anybody know what that means?
can anybody help me, PLEASE?

Thank you very much

Asgard