Which is a distribution of Linux, so the methods that I described should work. The big thing to watch out for is that how you set environment variables depends on which shell you're using. If your command-line prompt has a "$" at the end, it's probably Bourne shell. If it's a "%" it's the C shell or one of its derivatives.
It's possible that the CPATH variable may already be set. To check this, give the command "echo $CPATH". If there's something there, you probably don't want to replace it with your include-file directory, but rather, add the directory to the beginning of the list. To do this, give the following command (for C shell; make a similar change for the Bourne shell version)
setenv CPATH "/your/include/directory:$CPATH"
(In general, CPATH contains a list of directories, separated by colons.)
Then that's your compiler!

Actually the formal name is "GNU C++" but everybody calls it "g++".