how to use the c# scriptor in application

What you're looking for is the CSharpCodeProvider to compile the code and then you can use AppDomains if you want to run it plug-in style. You have to implement the events using MarshalByRefObject to cross AppDomain boundaries and then use serializable EventArgs descendants as parameters or you won't be able to unload the domains later.

This is rather complicated to implement - unfortunately my existing code is application-specific, but here a few snippets that can help:

To compile the code (has to be a complete .cs file with usings and all) into a dll:

var cc = new CSharpCodeProvider(new Dictionary<string,>() { { "CompilerVersion", "v3.5" } });
var outputpath = BinaryFolder + TargetAssembly + ".dll";

CompilerParameters cp = new CompilerParameters()
{
OutputAssembly = outputpath,
WarningLevel = 3,
GenerateExecutable = false,
GenerateInMemory = false,
CompilerOptions = "/target:library /optimize"
};

cp.ReferencedAssemblies.Add(
"System.dll", "System.Data.dll", "System.Xml.dll", "mscorlib.dll",
"System.Windows.Forms.dll");

To execute the code from the dll that you have compiled:
var _domain = AppDomain.CreateDomain("Isolated:" + Guid.NewGuid());

var _value = (IExecute)_domain.CreateInstanceAndUnwrap(AssemblyName, "Full name of the class in the dll here", false, BindingFlags.CreateInstance | BindingFlags.Default, null, null, null, null, null);
//_value.Properties = assign them here;

_value.Execute();

Further, you have to create a class based on an interface and then use only the interface in the calling code (main app) and implement the class in the .cs file. If you use any virtual (override) methods you will not be able to unload the appdomain (plug-in) later.

Hope this gives you a point to begin...