How to modify .bashrc .profile or .bash_profile?

Hi, I'm just getting familiar with unix like systems so excuse me if I annoy anybody!

I'm trying to modify something like the .bashrc, or .profile files in my mac to include some lines that would allow me to run a compiler properly, but I cannot find these files in my directories... (yes I'm using the command ls -a) so I looked it up in the internet and I found some references to modifying the etc/paths file with vim, except that vim won't let me modify it argumenting that it is a readonly file, so I guess I should change permissions with chmod over this file or maybe do it as the root user, but wanted to check if somebody knows a better way or if I'm just doing it wrong!

Thanks in advance.