I have a simple player class with 3 string properties and is inheriting from BindableBase class. This class will help me to implement the INotifyPropertyChanged interface in every property, just like this:

private string description;
public string PlayerDescription
     {
         get { return description; }
         set { this.SetProperty(ref description, value); }
     }

public class PlayersViewModel
{
    private ObservableCollection<Player> barcelonaPlayers = new ObservableCollection<Player>()
    {
           new Player{PlayerName=”Muniesa”, PlayerImage=@”Assets/Players/1.jpg”, PlayerDescription=”Lorem ipsum”},
         new Player{PlayerName=”Abidal”, PlayerImage=@”Assets/Players/2.jpg”,PlayerDescription=”Lorem”},
         new Player{PlayerName=”Adriano”, PlayerImage=@”Assets/Players/3.jpg”,PlayerDescription=”Lorem”},
         new Player{PlayerName=”Alexis”, PlayerImage=@”Assets/Players/4.jpg”,PlayerDescription=”Lore”},
         new Player{PlayerName=”Alves”, PlayerImage=@”Assets/Players/5.jpg”,PlayerDescription=”Lorem”},
         new Player{PlayerName=”Bartra”, PlayerImage=@”Assets/Players/6.jpg”,PlayerDescription=”Lorem “},
         new Player{PlayerName=”Busquets”, PlayerImage=@”Assets/Players/7.jpg”,PlayerDescription=”Lorem”},
         new Player{PlayerName=”Cuenca”, PlayerImage=@”Assets/Players/8.jpg”,PlayerDescription=”Lorem”},
         new Player{PlayerName=”Dos Santos”, PlayerImage=@”Assets/Players/9.jpg”,PlayerDescription=”Lorem”},
         new Player{PlayerName=”Fabregas”, PlayerImage=@”Assets/Players/10.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Iniesta”, PlayerImage=@”Assets/Players/11.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Jordi Alba”, PlayerImage=@”Assets/Players/12.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Mascherano”, PlayerImage=@”Assets/Players/13.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Messi”, PlayerImage=@”Assets/Players/14.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Montoya”, PlayerImage=@”Assets/Players/15.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Pedro”, PlayerImage=@”Assets/Players/16.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Pinto”, PlayerImage=@”Assets/Players/17.jpg”,PlayerDescription=”Lore”},
       new Player{PlayerName=”Pique”, PlayerImage=@”Assets/Players/18.jpg”,PlayerDescription=”Lorem”},
       new Player{PlayerName=”Puyol”, PlayerImage=@”Assets/Players/19.jpg”,PlayerDescription=”Lorem”},

    };

    public ObservableCollection<Models.Player> BarcelonaPlayers
    {
        get { return barcelonaPlayers; }
    }
}

1. Add a reference to your portable class library on both projects.
2. Click on the list (GridView or LongListSelector)
3. Go to properties and click on new DataContext on the properties tab
4. Select PlayersViewModel as new DataContext
5. Go to the properties tab again and click on the small white square that you will see just on the right of the ItemsSource property and in the context menu that will appear select CreateDataBinding, just like this: