Path setting for .net framework4

Hey frndz am using .net framework 4 for c# programing.... and visual studio 2010 also. But for programs in which i need to supply command line argument gives error in visual studio 2010, so i thought of setting my path in environment variable,so that i can do it from cmd prompt. But even after setting path when I went to cmd and typed csc -? to check if path has been set correctly?
it didn't recognized the command.

So can anyone tell me a stepwise procedure for setting the path?