declare Genric type via reflection

Question

hi,
i like to know about how to instantiate generic object with reflection
pls find my example,

I want to create an Object of "hello" with generic type "ClassABC"

//want to Create hello object,with generic type will declare at run time only
 
public void DoHello(String ClassName)
{
       Type TypeClassABC= Type.GetType(ClassName);

        hello _hello= new hello<TypeClassABC>();

}
But get a build error:

the type or namespace "TypeClassABC" could not be found,