How about more information?
Is it this software you are talking about? http://roadmap.digitalomaha.net
Which gcc version you are using? On what platform? And what is the target platform? (ie after compliation where you wanna run the program file)
Usually if you are not developing from scratch, a source code package usually includes a Makefile. The makefile should define all useful/proper flags passed to the gcc compiler. So, maybe it is not that helpful to read the gcc doc afterall. Do you have a specific question about gcc in mind?