show slow textbox array ie display the item and wait a few seconds to display the following c # , its gonna be like a process

roundd 1 //wait a few seconds to dislplay another line

         for (i = 1; i <= r; i++)
        {

            label3.Text += ("round " + Convert.ToInt32(i) + Environment.NewLine);

            for (j = 0; j <= n; j++)
            {

                if (b[j] > 0)
                {
                    b[j] = b[j] - q;
                    if (b[j] <= 0)
                    {
                        b[j] = 0;
                        label3.Text += ("proceso  " + Convert.ToInt32(j) +"  completado  "+ Environment.NewLine);

                    }
                    else
                        label3.Text += ("process" + j.ToString() + "remaining time is" + Convert.ToInt32(b[j]) + Environment.NewLine);

                }

Don't know exactly what you are trying to achieve.
Line 1 should be for (int i = 1; i <= r; i++)
Same for j on line 6. Unless you declared i and j as int elsewhere.
Line 4 Convert.ToInt32(i) should bei.ToString(), same with all other converts. i and j are integers, why convert them to integers?

all is integer Convert.toInt32, the string is a mistake, I need that the result of the code ^(up) is display slow line by line like it:

mean that the label where I deployment unfolds each result waiting 3 seconds to display each line