This gives me to solve this...
class nameex
public object call()
dynamic expando = new ExpandoObject();
var p = expando as IDictionary<String, object>;
p["Demo"] = "New val 1"; }
class de
dynamic n = new nameex();;
n.Demo = "Welcome";

Please use code tags around your code.

There are several errors with this code:

1) call() does not return a value, it should return an object
2) I am not sure why you are using the 'dynamic' keyword for your expando object, could you not simply use 'var' or its actual type?
3)class de contains no methods - rather it looks like you wrote a method as the class body.