compile.bat
edit path point to csc.exe (where you installed Microsoft.NET\Framework) (or setup the path variables see reference link)
edit flags for csc as required i.e. /reference

notepad++setting.txt
edit path point to compile.bat and paste it in notepad++ run

compile and run C# file in the same path as the .cs source

notepadcsharp.zip

reference:
http://dotnet.dzone.com/articles/notepad-c-compiler-you-can-do