How do I use the platform SDK with C#?

I have installed the MS Platform SDK, in the hopes of using the Setup API to work with .ini files. My problem though, is how do I use the functions defined in the API? I have set it up, and registered the paths with VS, but I can't seem to locate the files. Do I "Using PlatformSDK" or somesuch? Does anyone know the appropriate "using" command? Thanks in advance Roger