How are XAML object property values ​​set?

Question

Programming

Good evening.
I just can't understand how the properties of objects are set, for example, Foreground or Margin?
Code example:

public MainPage()
        {
            this.InitializeComponent();
            TextBlock story = new TextBlock();
            story.Text = "TestTestTest";
            story.FontSize = 22;
            story.Margin = "???";
            story.Foreground = "???";
            body.Children.Add(story);
        }

These methods cause an error:

textBlock.Foreground = new SolidColorBrush(Color.FromRgb(0, 0, 255));

или

textBlock.Foreground = Brushes.Blue;

Answer 1

story.Margin = new Thickness(0,5,0,5);
story.Foreground = new SolidColorBrush(Colors.LimeGreen);

Answer 2

What mistake? namespace not added or what?
All 3 methods mentioned in this thread work.

Answer 3

using Windows.UI; // для Colors
using Windows.UI.Xaml.Media; // для SolidColorBrush