Error messages are always useful to post whenever you have a problem. It really helps determining what could be the problem.
Back to your problem: gcc depends on a whole slew of other packages, which in turn depends on others. This is known as "rpm hell".
Installing just gcc won't cut it, you need to install a whole basic development environment. I haven't used it, but from posts here I am led to believe that RedHat in fact does have some sort of graphical, easy-to-use package manager. That should allow you to install gcc and its dependencies.
Or, copy over all the rpms listed as dependencies to the same directory as gcc and do an rpm -ivh *.rpm