You have to calculate the positions of the textboxes using cos and sin.
This creates 20 textboxes arranged in a circular pattern.
int radius = 200;
for (int i = 1; i < 20; i++)
{
TextBox tb = new TextBox();
tb.Left = (int)(Math.Cos((double)i) * radius) + radius;
tb.Top = (int)(Math.Sin((double)i) * radius) + radius;
this.Controls.Add(tb);
}
Hope this helps