<Grid Name="field" Tag="gameField" Margin="6,60,386,0" Height="400" VerticalAlignment="Top">
        <Grid.RowDefinitions>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
            <RowDefinition/>
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition/>
            <ColumnDefinition/>
            <ColumnDefinition/>
            <ColumnDefinition/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>
        <Button x:Name="button00" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="0" Grid.Column="0" Click="button_Click"/>
        <Button x:Name="button01" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="0" Grid.Column="1" Click="button_Click"/>
        <Button x:Name="button02" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="0" Grid.Column="2" Click="button_Click"/>
        <Button x:Name="button03" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="0" Grid.Column="3" Click="button_Click"/>
        <Button x:Name="button04" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="0" Grid.Column="4" Click="button_Click"/>

        <Button x:Name="button10" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="1" Grid.Column="0" Click="button_Click"/>
        <Button x:Name="button11" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="1" Grid.Column="1" Click="button_Click"/>
        <Button x:Name="button12" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="1" Grid.Column="2" Click="button_Click"/>
        <Button x:Name="button13" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="1" Grid.Column="3" Click="button_Click"/>
        <Button x:Name="button14" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="1" Grid.Column="4" Click="button_Click"/>

        <Button x:Name="button20" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="2" Grid.Column="0" Click="button_Click"/>
        <Button x:Name="button21" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="2" Grid.Column="1" Click="button_Click"/>
        <Button x:Name="button22" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="2" Grid.Column="2" Click="button_Click"/>
        <Button x:Name="button23" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="2" Grid.Column="3" Click="button_Click"/>
        <Button x:Name="button24" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="2" Grid.Column="4" Click="button_Click"/>

        <Button x:Name="button30" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="3" Grid.Column="0" Click="button_Click"/>
        <Button x:Name="button31" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="3" Grid.Column="1" Click="button_Click"/>
        <Button x:Name="button32" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="3" Grid.Column="2" Click="button_Click"/>
        <Button x:Name="button33" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="3" Grid.Column="3" Click="button_Click"/>
        <Button x:Name="button34" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="3" Grid.Column="4" Click="button_Click"/>

        <Button x:Name="button40" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="4" Grid.Column="0" Click="button_Click"/>
        <Button x:Name="button41" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="4" Grid.Column="1" Click="button_Click"/>
        <Button x:Name="button42" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="4" Grid.Column="2" Click="button_Click"/>
        <Button x:Name="button43" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="4" Grid.Column="3" Click="button_Click"/>
        <Button x:Name="button44" Content="" HorizontalAlignment="Left" VerticalAlignment="Top" Width="80" Height="80" Grid.Row="4" Grid.Column="4" Click="button_Click"/>

    </Grid>

private void button_Click(Object sender, RoutedEventArgs e)
    {
        Button[,] Field = new Button[5, 5] { {button00, button01, button02,  button03,  button04},
                                             {button10, button11, button12,  button13,  button14},
                                             {button20, button21, button22,  button23,  button24},
                                             {button30, button31, button32,  button33,  button34},
                                             {button40, button41, button42,  button43,  button44}
                                          };

        for (int i = 0; i < 5; i++)
        {
            for (int j = 0; j < 5; j++)
            {
                if (Field[i, j] == sender)
                {
                 Field[i, j].Background = Brushes.Red;
                }
            }
        }
    }