How to I display the calculated total of all values in a certain column in a listview

This should not be too difficult to set up.

//Define a class to store the data. The entities, Name and Price, need to be defined as properties 
//so that they can be bound to controls.
public  class Product
  {
      public string Name { get; set; }

      public double Price { get; set; }


  }

//Define a view model to act as the DataContext for the Window
//The view model needs to have a collection to store the products, a SelectedProduct property and a TotalPrice property.
namespace ListViewSelect
{
    using System.Collections.ObjectModel;
    using System.Collections.Specialized;
    using System.ComponentModel;
    using System.Linq;
    using System.Windows.Input;
    // Install the following reference using Nuget
    //It will also  install the Prism.SharedIterfaces.dll
    using Microsoft.Practices.Prism.Commands;
    public class ProductsVM : INotifyPropertyChanged
    {
     private ObservableCollection<product> itemsSource;
     public ObservableCollection<product> ItemsSource
        {
            get
            {
                return this.itemsSource;
            }
            set
            {
                this.itemsSource = value;
                this.NotifyPropertyChanged("ItemsSource");
            }
        }
     private Product selectedProduct;

     public Product SelectedProduct
        {
            get
            {
                return this.selectedProduct;
            }

            set
            {
                this.selectedProduct = value;
                this.NotifyPropertyChanged("SelectedProduct");
            }
        }

     private double totalPrice;

     public double TotalPrice
        {
            get
            {
                return this.totalPrice;
            }

            set
            {
                this.totalPrice = value;
                this.NotifyPropertyChanged("TotalPrice");
            }
        }
//There needs to be a Command property that can be bound to the  main window’s ‘Add’ button,
   public ICommand AddProductCommand { get; private set; }

// A PropertyChangedEvent notifies the window when a property changes in the view model 
   public event PropertyChangedEventHandler PropertyChanged;

//This fires the PropertyChanged event
   private void NotifyPropertyChanged(string propertyName)
        {
            if (this.PropertyChanged != null)
             {
                this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }


//The view model’s constructor initialises everything.
   public ProductsVM()
        {
            this.AddProductCommand = new DelegateCommand<object>(this.AddProduct);

            this.itemsSource = new ObservableCollection<product>
            {
                new Product { Name = "A", Price = 1 },
                new Product { Name = "B", Price = 2 },
                new Product { Name = "C", Price = 3 }
            };
           //The view model subscribes to the Collection changed event   
            this.itemsSource.CollectionChanged += this.itemsSource_CollectionChanged;
            this.updateTotalPrice();
        }

//The AddProduct method adds a Product to the collection.
   private void AddProduct(object sender)
        {
            this.ItemsSource.Add(new Product { Name = "Z", Price = 20 });
        }

//The subscription to the Collection changed event of the collection 
//results in the event calling  the itemsSource_CollectionChanged method.

   private void itemsSource_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            this.updateTotalPrice();
        }

   private void updateTotalPrice()
        {
            //using Linq
            double total = this.itemsSource.Sum(p => p.Price);
            //using foreach
            // double total =0;
            //foreach (Product p in this.itemsSource)
            //{
            //    total += p.Price;
            //}

            this.TotalPrice = total;
        }
  }
}
//Set the main windows xaml as follows
<window x:class="ListViewSelect.MainWindow" xmlns:x="#unknown">
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
      Title="MainWindow" 
      xmlns:local="clr-namespace:ListViewSelect" >
    <!--xmlns:local is a reference to the namespace in which the view model is defined-->
    <window.datacontext>
        <local:productsvm xmlns:local="#unknown" />
    </window.datacontext>
    <grid>
        <stackpanel>
            <textblock text="{Binding TotalPrice}" margin="5,0,0,0" fontsize="21.333" fontfamily="Tahoma" fontweight="Bold" />
            <listview itemssource="{Binding ItemsSource}" selecteditem="{Binding SelectedProduct, Mode=TwoWay}" issynchronizedwithcurrentitem="True">
                HorizontalAlignment="Center" Height="168"  VerticalAlignment="Top" Width="400" Background="#FFBFBFBF">
             
                <listview.view>
                    <gridview x:name="orderDetailsGridView">
                        <gridviewcolumn width="280" header="Product Name" displaymemberbinding="{Binding Path=Name}" />
                        <gridviewcolumn width="60" header="Price" displaymemberbinding="{Binding Path=Price}" />
                    </gridview>
                </listview.view>
            </listview>
            <textblock text="{Binding SelectedProduct.Name}" margin="5,0,0,0" fontsize="21.333" fontfamily="Tahoma" fontweight="Bold" />
     <button command="{Binding AddProductCommand}">Add</button>
        </stackpanel>
    </grid>
</window>

</product></object></product></product>