Basically I have 2 classes (class Dog and class DogChorus) and i am trying to change the getoutput() because i want it to display a message box with a message telling the number of lesg that all dogs have and it should returns details of all dogs creat

    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    namespace HelloDogs
    {
        class DogChorus
        {
            Dog breed;
            Dog dogHeight;

            public DogChorus()
            {
                breed = new Dog();
                dogHeight = new Dog();
                dogHeight.SetSound("Ruff!");
            }

            public string GetOutput()
            {

                return dogHeight.dogSpeech() + " \n " + breed.dogSpeech();
            }

        }
    }

    2eme class:

       class Dog
        {
            private string barkSound;
            private string breed;
            private int dogHeight; 
            private string dogColour;
            private static int noOfLEgs;


            public string Breed
            {
                get { return breed; }
                set { breed = value; }
            }

            public int DogHeight
            {
                get { return dogHeight; } 
                set { dogHeight = value; } 
            }

            public string DogColour
            {
                get { return dogColour; } 
                set { dogColour = value; } 
            }

            public static int NoOfLEgs
            {
                get { return Dog.noOfLEgs; } 
                set { Dog.noOfLEgs = value; } 
            }

            private string dogSpeech;

            public Dog()
            {
                barkSound = "Woof!";
                breed = "cocker spaniel";
                dogHeight = 15;
                dogColour = " Brown";
            }

            private bool IsBig(int size)
            {
                bool Size1;

                if (size < 50)
                {
                    Size1 = false;
                }
                else
                {
                    Size1 = true;

                }
                return Size1;
            }


               public string GetSpeech(int theDog)
            {
                if (IsBig(theDog))
                {

      dogSpeech = "Hello. I am a " + breed + ". I am big and I mesure.  " + dogHeight + ". I am ." + dogColour + barkSound;
                    return dogSpeech;

             }
                else
                {
                    dogSpeech = "Hello. I am a " + breed + ". I am small. " + dogHeight + ". I am ." + dogColour + barkSound;
                    return dogSpeech;
                }
            }
            public void SetSound(String barkSound)
            {
                this.barkSound = barkSound;
            } 
        }
    }

1.Set dogchors.goheight=20
2.Call getSpeech method.Remove the parameter of getspeech() method and isbig()

Reason:
as you already setting the value of dogheight,so when you call getspeech method then call will go to isbig() method,isbig will pick dogheight from dogheight porperty.