For a good breakdown of directory structure, take a look at:
The /bin directory contains binaries (executables) that are used in single-user systems. For multi-user systems these binaries are usually stored in the /usr/bin directory.
You can usually locate a binary by using the whereis command in a terminal windows. For example, if you installed the apt-get RPM, you could enter:
At a terminal prompt, and a list of locations would be returned. The location that is of interest to you is /bin/apt-get or /usr/bin/apt-get.
Hope this helps!