If you cannot access the GNU compiler for this course (g++) then you need to modify the "path" that Unix searches when it looks for software that you can use. The full path to g++ is /opt/gcc-4.1.1/g++, but using the full path won't help unless your path also includes library information.
The IT staff have set up a system that reads a file in your home directory when you first login. You can use this file to modify your path.
The file is in the class "resources" directory, and is called .localenv
Note that the name starts with a dot. If you already have a .localenv file in your home directory, then add the contents of this one to the end of it using emacs or other method. If you do not have such a file in your home directory, you can just copy this one.
After you change the .localenv file, you must log out and in again for the changes to take effect.