How can I set Annotation in n-hibernate Forward Engineering

In Java I can easily set an annotation
as for example

@Entity
Class User
{
String name;
...//geter
...//seter
}

Here @Entity is an annotation
I can be able to create a table name User and as User is set as @Entity annotation.
 
Similarly how can I able to set a c# class as Entity. Means How I make an @Entity annotation for a class?
kindly help me.
Also if any body know ,kindly tell me ,is there any annotation use for forward engineering in n-Hibernate?