Margin w Windows forms

Cześć pisze gre aranoid i chciałbym aby kafelki byly losowo umieszczne jest tylko jeden progrem nachodzą na siebie i chcialbym to naprawić ale nie wiem jak znaczy chcialbym ustawic margin dla kazdego ale nie dziala nie wiem czemu moze mi ktos wytlumaczyc dlaczego margin nie dziala albo jak w inny sposob mozna to naprawić :)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp58
{
    public partial class Form1 : Form
    {

        public const int col = 5;
        public const int row = 3;
        
        public PictureBox[,] blocks;
        public Form1()
        {
            setBlock();
            InitializeComponent();
            Cursor.Hide();
        }

        Random r = new Random();

        


        private void setBlock()
        {
            int w = 100, h = 100;

            blocks = new PictureBox[row, col];

            for (int i = 0; i < row; i++)
            {
                for (int j = 0; j < col; j++)
                {
                    blocks[i, j] = new PictureBox();
                    blocks[i, j].Width = w;
                    blocks[i, j].Height = h;
                    blocks[i, j].BackColor = Color.DarkBlue;

                    blocks[i, j].Top = r.Next(0, 400);
                    blocks[i, j].Left = r.Next(0, 1000);

                    this.Controls.Add(blocks[i, j]);

                }
            }
        }



        int speed_x = 4;
        int speed_y = 4;

        private void Timer1_Tick(object sender, EventArgs e)
        {
            ball.Top += speed_y;
            ball.Left += speed_x;

            if(ball.Bottom >= panel.Bottom)
            {
                timer1.Stop();
            }

            if(ball.Right >= panel.Right || ball.Left <= panel.Left)
            {
                speed_x = -speed_x;
            }

            if(ball.Top <= panel.Top)
            {
                speed_y = -speed_y;
            }

            if(ball.Bounds.IntersectsWith(Racket.Bounds))
            {
                speed_y = -speed_y;
            }


            for(int i=0; i<row; i++)
            {
                for (int j = 0; j < col; j++)
                {
                    if ((ball.Bounds.IntersectsWith(blocks[i, j].Bounds)) && (blocks[i, j].Visible == true)) {

                        blocks[i, j].Visible = false;
                        speed_y = -speed_y;
                        speed_x = -speed_x;
                    }
                }
            }
        }

        private void Panel_MouseMove(object sender, MouseEventArgs e)
        {
            Racket.Left = e.Location.X - (Racket.Width/2);

            
        }
    }
}

```C#