Oh, very bad question.
Because there is shining through that you want to go to damage your system.
You can update this library only with installing a newer distribution or you are going to compile a newer library and linux system on an other partition or drive.
How to compile a new Linux system is described by Linux From Scratch LFS,
Your libstdc (++) is located in /lib and the link libc.so.6 is pointing to the system version.
What is included in that library is described by GNU's glibc package.