this Keyword

You should use the "this" keyword when you want to refer to the instance itself

public class MyClass 
{ 
   private int _myInteger; 

   public MyClass() 
   { 
      this._myInteger = 20; 
   } 

   public int Method_Multiply(int value1) 
   { 
      return value1 * this._myInteger; 
   } 
}