public class MusicService : IMusicService
    {
        DataClassesDataContext Data { get; set; }
        public MusicService()
        {
            Data = new DataClassesDataContext();
        }
        public List<User> GetUser(string login)
        {
            var q = from a in Data.Users where a.login==login select a;
            return q.ToList();
        
    }

public partial class MainPage : PhoneApplicationPage
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
        {
            MusicServiceClient serviceClient = new MusicServiceClient();
            serviceClient.GetUserCompleted += serviceClient_GetUserCompleted;
            serviceClient.GetUserAsync(login.Text);
        }

        void serviceClient_GetUserCompleted(object sender, GetUserCompletedEventArgs e)
        {
            if (e.Result != null)
            { 
                listbox1.ItemsSource = e.Result;
            }
        }
    }

    <phone:PhoneApplicationPage.Resources>
        <DataTemplate x:Key="TestDataTemplate">
            <StackPanel Orientation="Horizontal">
                <TextBlock Margin="10" Text="{Binding login}"></TextBlock>
                <TextBlock Margin="10" Text="{Binding password}"></TextBlock>
            </StackPanel>
        </DataTemplate>
    </phone:PhoneApplicationPage.Resources>

<ListBox Grid.Row="0" ItemsSource="{Binding}" ItemTemplate="{StaticResource TestDataTemplate}" Height="Auto" Width="400" VerticalAlignment="Top" HorizontalAlignment="Center" Margin="10,10,0,0" Name="listbox1"></ListBox>

create table Users
(
id_user integer IDENTITY(1,1) primary key,
login varchar (200) unique not null,
password varchar(200) unique not null
);

create table Songs
(
id_song integer IDENTITY(1,1) primary key,
song_name varchar(200) not null,
CONSTRAINT uc_SongID UNIQUE (id_song,song_name)
);

create table UsersSongs
(
id_user integer,
id_song integer,
CONSTRAINT pk_userssongs PRIMARY KEY (id_user,id_song),
CONSTRAINT fk_us_users FOREIGN KEY (id_user)
REFERENCES Users(id_user),
CONSTRAINT fk_us_songs FOREIGN KEY (id_song)
REFERENCES Songs(id_song)
);