How to specify parent properties of a control in code behind C#

[SimonORorke]

How can I add parent properties to a control in code behind C#? I'm not sure 'parent properties' is the correct terminology. So first let me give an example of assigning parent properties in axaml:

<Canvas>
    <Rectangle
        Fill="Blue" Height="100" Width="100"
        Canvas.Left="50" Canvas.Top="20"/>
</Canvas>

But I want to do it in code behind. So the axaml becomes a mere stub, like this

<Canvas x:Name="Canvas" />

And this is as far as I have got with the C#:

Canvas.Children.Add(new Rectangle {
    Fill = Brushes.Blue,
    Height=100,
    Width=100,
});

So, in this example, how can I specify Canvas.Left="50" and Canvas.Top="20" for the Rectangle in the code behind?

[rabbitism]

This is not about parent, but the AttachedProperty system in xaml.

Specific to this question, you can simply call

Canvas.SetTop( yourRectangle, 10);

Notice that this is a static method, the Canvas here is class name, not instance name.