If you install any programs, most likely it will put its binaries in /usr/bin and the libraries in /usr/lib.
If you want to compile and install any source code you have downloaded you have to do:
--> go to its folder
It should install its files directly in /usr.
If you are compiling a program of your own and you want to install it, you should either put in a folder that is in the PATH or copy it to /usr/bin.
I'm not sure what you really want to know, hope this helps.