I am a noob in oop as well as in C#. Consider A scenario in OO case like the following:

Package A

public class A {
   constructor a(){
     B b = new B(); // I want to instantiate `b` when i have instantiated `a`
                   // and i want to work with each `b` against each `a` 
                   // is this the way to do that??**and assume classA inherits 
                  // something else.
   }
}

public class B 
{}

Package B

using package A;

class M{
   public main(){
      A a = new A();
      //how can i use `b` here ?
   }
}

I have used pseudo code to outline some of the idea i want implement. But i dont know how do i do that. If its a wrong implementation or it can be done in a lot easier way, please show me how?