How can I manipulate margins in C # dynamically?

I would like to know how to give margins to the pictureBox in C #, I currently have this code:

    posX = posX + 100;
    PictureBox pic = new PictureBox();
    pic.Location = new Point(posX, 50);
    pic.Name = "pic" + z;
    pic.Size = new Size(100, 100);
    pic.ImageLocation = directoriosE[z];
    pic.Margin = new Padding(100); --- deberia setear un valor al padding

In the last line I'm doing an equalization from margin to padding, but I did not find any function that was like this new Margin(100); and it was the only one that came closer, anyway it does not generate the setting of margins like me I was waiting.

Example of the current window.

As you can see, I would like to separate by means of margins each of my elements that is generated through a for cycle.

Also do it with the following code:

        Thickness margin = pic.Margin;
        margin.Left = 10;
        pic.Margin = margin;

But I got the following error:

  

Can not find the name or type of namespace   Thickness, missing a using directive or an assembly reference

I also did it in the following way:

 pic.Margin = new Padding(50,50,50,50);

But in the same way I do not apply the margin I am asking for. If I debug my application and position myself on my pic in the line where I set the maregenes, it gives me the following: