How to link C# with XAML?

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XAML

I am new on this world and I have created this code in Xamarin forms, however I am not able to link the answer given in the visual Xamarin with the C# code. Any suggestion, please? Thanks
This is the code in C#

public MainPage()
       {
           InitializeComponent();
           Button button = new Button
           {

               HorizontalOptions = LayoutOptions.Center,
               VerticalOptions = LayoutOptions.Center

           };

           button.Clicked += async (sender, args) =>
           {
               await Navigation.PushAsync(new MainPage());

           };

       }
       public void Button_Click(object sender, EventArgs e)
       {

       }

   }

   namespace animal
   {
       class animaltype
       {

           public static string Name(string a)
           {
               if (a == "Dog")
               {
                   a = "oh that's cool";

                   return a;
               }
               else
                   a = " Pets are good company help to live longer";
               return a;


           }

       }
   }

This is the code in XAML

<StackLayout>
       <Frame BackgroundColor="#2196F3" Padding="24" CornerRadius="0">
           <Label Text="Welcome to Namespaces!" HorizontalTextAlignment="Center" TextColor="White" FontSize="36"/>
       </Frame>

       <Label x:Name="dogbreed1"  Text=" what type of dog breed do you have?" FontSize="Title" Padding="30,10,30,10"/>


       <Entry x:Name="dogbreed"  Placeholder="Enter text" />

       <Button Text="Click here to see answer" Clicked="Button_Click"
               Margin="5"
                HorizontalOptions="Center"
               VerticalOptions="Center"
               FontSize="Large"
               TextColor="Blue"/>

       <Label x:Name="question"
              Text="Answer" HorizontalTextAlignment="Center" TextColor="Blue" FontSize="36"/>

       <Label Text="" FontSize="16" Padding="30,0,30,0"/>
       <Label FontSize="16" Padding="30,24,30,0">

What I have tried:

I have changed the name of variable a by doing this way

if (Entry.dogbreed == "German Shepperd")
                {
                    Label.question = "oh that's one of the smartest ones";

                    
                }

I have tried to substitute the variable a equal to Entry.dobreed, but it doesnt work, either. Thanks
but it hasnt work