[CentOS] gtk+-2 and centos 5

I'm a bit confused about how to compile somethingon Centos 5 that's looking for gtk +-2.

./configure errors out with this message:

checking for GTK+ - version >= 2.4.0... no *** Could not run GTK+ test program, checking why... *** The test program failed to compile or link. See the file config.log for the *** exact error that occured. This usually means GTK+ is incorrectly installed. configure: error: Cannot find GTK2

The best information I could find on Google tells me this:

"Edit the script file , it is looking for gtk+-2 while you have gtk2 installed."

That's nice, but how? I edited the "configure" script and changed all references to read gtk2 and that did me no good at all.

How can I address this issue?