How to Access method in Parent from Child Class

How to Access method in Parent from Child Class

I have one method which is in child class and I want to fetch that in
Parent with the help of this.
public class Class1
{
private class Class2
{
public void Add(int a, int b) // Method in Class 2
{
this.Add(a, b);
}
}
public Class1() // constructor of Class 1
{
// Get this Add method by This.Add ??
// Not able to fetch the Add method here.
}
}